A Highly Efficient and Large-Scale Artificial Breeding Method for Long-snout Catfish

Abstract

This invention relates to the field of aquaculture technology, specifically to a highly efficient and large-scale artificial breeding method for *Catfish bream*. The method includes a seedling cultivation step; the water in the seedling tank is obtained by treating fresh aquaculture water with fertilization, and the water in the seedling tank contains initial feed for *Catfish bream* fry; the initial feed includes rotifers and cladocerans. The fertilization method involves: after filling the seedling tank with fresh aquaculture water, sprinkling soybean milk, a dispersion of bacterial and algal nutrient paste, and a dispersion of algal polypeptides onto the water surface, and then adding rotifers to the water in the seedling tank. This technical solution can solve the technical problems of existing artificial breeding techniques for *Catfish bream*, which have many weaknesses and cannot meet the demands of modern aquaculture for efficient, stable, and high-quality seedling production. This technical solution has the advantages of improving breeding efficiency, ensuring seedling quality, adapting to large-scale production, reducing costs, and being environmentally friendly, making it suitable for efficient and large-scale artificial breeding of *Catfish bream*.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, specifically to a highly efficient and large-scale artificial breeding method for long-snout catfish. Background Technology

[0002] Long-snouted catfish ( Leiocassis longirostris The long-snout catfish (Leiocassis hainanensis), belonging to the order Siluriformes, family Bagridae, and genus Leiocasssis, is a valuable freshwater fish in my country. It is widely distributed naturally, with wild populations mainly inhabiting major river systems such as the Yangtze, Liao, Huai, Min, and Pearl Rivers. This fish is renowned for its few intramuscular bones, tender flesh, and delicious flavor, earning it the reputation of "one who hasn't eaten long-snout catfish doesn't know the taste of fish," making it highly popular and well-regarded in the market. Furthermore, its thick and tough swim bladder, after processing, can be made into the traditional and prized ingredient "penholder fish maw," considered one of the "Three Treasures of Shishou," further enhancing its overall economic value. Since breakthroughs in artificial breeding technology in the 1980s, the aquaculture industry of long-snout catfish has developed rapidly, forming large-scale farming patterns in many regions. After decades of technological accumulation and model optimization, the current long-snout catfish farming system has shown characteristics such as high technological maturity, widespread application of standardized farming models, strong regional adaptability, and stable industrial benefits. Farming output continues to increase with technological progress and model innovation.

[0003] However, with the continuous growth of consumer market demand, the pressure on the supply of high-quality seedlings is becoming increasingly prominent. Problems such as inconsistent seedling quality, unstable breeding efficiency, and insufficient standardization of large-scale breeding technology have become major bottlenecks restricting the high-quality development of the industry. At present, although artificial breeding technology for long-snout catfish has been applied in some areas, the overall technical system still has many weaknesses, making it difficult to meet the urgent needs of modern aquaculture for efficient, stable, and high-quality seedling production.

[0004] In artificial breeding, although basic artificial spawning techniques have been mastered, hormone administration protocols (such as dosage, ratio, and injection timing) largely follow traditional models or draw on experience from other fish species, lacking optimized parameters specific to the physiological characteristics of the long-snout catfish. Operational procedures vary significantly across different regions, lacking unified technical standards, resulting in large batch-to-batch variations in artificial breeding. During the hatching and early fry rearing stages, existing technologies lack precise control over the hatching environment and systematic research on the biological characteristics of long-snout catfish fertilized eggs and larvae is insufficient. Problems such as egg membrane mold, embryonic malformation, and low hatching rates are common during hatching. More importantly, there is a lack of effective coordination and system integration between different stages, and a complete, replicable, and scalable technical system from parent stock management to fry release has not yet been formed. The fragmentation and reliance on experience in technology lead to inconsistent technical levels among different production units, making it difficult to achieve a large-scale, factory-like, and intelligent modern fry production model. Furthermore, the lack of supporting quality control standards and effectiveness evaluation mechanisms during technology promotion further limits the large-scale supply of high-quality fry.

[0005] Therefore, constructing a standardized and scalable breeding technology system that integrates parent selection, artificial spawning, fertilization and hatching, and seedling cultivation, and promoting its industrial application, has become an urgent need and key technology for improving the quality and efficiency and achieving sustainable development of the long-snout catfish farming industry. Summary of the Invention

[0006] The present invention aims to provide an efficient and large-scale artificial breeding method for long-snout catfish, in order to solve the technical problems that existing artificial breeding techniques for long-snout catfish have many weaknesses and are difficult to meet the needs of modern aquaculture for efficient, stable and high-quality seedling production.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A highly efficient and large-scale artificial breeding method for long-snout catfish includes the following seedling cultivation steps: placing long-snout catfish fry into a seedling pond for rearing; the water in the seedling pond is fresh culture water that has been treated with fertilizer, and the water in the seedling pond contains the first feed for the long-snout catfish fry; the first feed includes rotifers and cladocerans; The method for treating aquaculture water with fertilizer is as follows: after filling the seedling pond with fresh aquaculture water, sprinkle soybean milk, dispersion of bacterial and algal nutrient paste, and dispersion of algal polypeptide on the water surface. The amount of soybean milk used is 2.5-5 kg / mu·m per day, for 5 consecutive days; The dosage of the fungal and algal nutrient paste is 100-150 grams per mu·meter per day, and it should only be applied on the first day after applying the soybean milk. The dosage of algal polypeptide is 1.0-1.5 kg / mu·m per day, applied once every 5-7 days; Two to three days after the first application of soybean milk, algae nutrient paste dispersion, and algae-derived polypeptide dispersion to the water surface, apply 100-200 g / mu·m of rotifers to the water in the seedling pond. One to two days after the density of rotifers in the nursery reaches 10-20 individuals / mL and the density of cladocerans reaches 1-3 individuals / mL, the long-snout catfish fry are introduced into the nursery for cultivation.

[0008] Furthermore, during the rearing process of the long-snout catfish fry, the water quality conditions in the rearing pond are maintained as follows: dissolved oxygen ≥5mg / L, pH value 6.5-8.5, ammonia nitrogen ≤0.2mg / L, nitrite ≤0.1mg / L, sulfide ≤0.1mg / L, and transparency 25-35cm. The water in the seedling pond should be maintained at a flow rate of 0.1-0.2 m / s, and 10-15% of the water in the seedling pond should be replaced daily with fresh aquaculture water. Furthermore, one day before the long-snout catfish fry are placed into the nursery pond for rearing, vitamin stress reliever is sprayed onto the surface of the nursery pond at a dosage of 0.2-1 kg / mu·m. Soy milk is prepared by soaking soybeans for 10-12 hours at a volume ratio of water to soybeans of 2-3:1 to obtain soaked soybeans; when grinding, the soybeans are ground at a volume ratio of water to soaked soybeans of 2:1 to obtain soy milk.

[0009] Furthermore, the water quality conditions for the fresh aquaculture water injected into the seedling pond are: dissolved oxygen ≥5mg / L, pH value 6.5-8.5, ammonia nitrogen ≤0.2mg / L, nitrite ≤0.1mg / L, sulfide ≤0.1mg / L, transparency 25-35cm, and the aquaculture water is filtered through a 60-80 mesh screen. Before filling the seedling pond with aquaculture water, use a high-pressure water gun to remove silt and debris from the bottom of the pond, and then disinfect it with 360-500g of chlorine dioxide per acre. The seedling pond is a cement pond with an area of ​​1.0-2.0 mu and a water depth of ≥1.8m.

[0010] Furthermore, a feeding mechanism is provided in the seedling pond; The feeding mechanism includes a shaded canopy with its top and four sides covered by shading cloth. The canopy measures 1-2m in length, 1-1.5m in width, and 0.6-1.0m in height. A feeder with a light source is suspended in the center of the top of the canopy. The light intensity of the light source on the feeder is controlled at 200–400 μmol / m². 2 The distance between the light source and the water surface is controlled at 0.3-0.6m; The shade canopy is fixed to a micro-flow device at the bottom; the micro-flow device is fixed above the water surface by supporting legs; the distance between the top of the shade canopy and the water surface is ≤1.2m; the micro-flow device is used to drain water into the seedling pond to create a micro-flow environment; Fish fry hiding places are randomly placed in the water below the feeding facility.

[0011] Furthermore, in the seedling cultivation process, the method of feeding artificial feed to the long-snout catfish fry is as follows: During the larval stage of the long-snout catfish: Longsnout catfish fry were fed with powdered feed, which was sieved through a screen with a mesh size of ≥80. The feed amount accounted for 5-8% of the fry's body weight, and the protein content of the powdered feed was 46-48%. In the juvenile stage I of the long-snout catfish fry: For the first 3-5 days, the feed should be gradually changed from powdered feed to microparticle feed; the protein content of microparticle feed is 46-48%; On the first day of the first stage of juvenile fish, feed them 90%-95% powdered feed and 5%-10% microparticle feed. Then, gradually increase the proportion of pelleted feed every day until the third to fifth day when they are fed 100% microparticle feed. Then continue feeding with microparticle feed until the end of stage I fry; the microparticle feed is sieved through a ≥60 mesh screen; In the juvenile stage II of the long-snout catfish fry: For the first 3-5 days, the feed should be transitioned from microparticle feed to pellet feed; the protein content of the pellet feed should be 40-48%; the particle size of the pellet feed should be 1-2 mm. On the first day of the second stage of juvenile fish, feed them 90%-95% microparticle feed and 5%-10% pellet feed. Then, gradually increase the proportion of pellet feed each day until the third to fifth day when they are fed 100% pellet feed.

[0012] Furthermore, in the seedling cultivation process, the method of feeding artificial feed to the long-snout catfish fry is as follows: During the larval stage of the long-snout catfish: Four to five days after hatching, a continuous feeding pattern with the lights on all day was adopted. Six to seven days after hatching, the lights should be on all day and the food should be fed twice a day at set times. In the juvenile stage I of the long-snout catfish fry: The fish were kept lit all day and fed three times a day at set times. The total daily feed amount as a percentage of the fish fry's body weight was gradually increased from 5%-8% to 8%-12% each day. In the juvenile stage II of the long-snout catfish fry: The fish are kept lit all day and fed three times a day at set times; the total daily feed amount accounts for 10-15% of the fish fry's body weight.

[0013] Furthermore, during the larval stage of the long-snout catfish (4-7 days after hatching), the stocking density is 100,000-150,000 fish per acre. From 6-7 days after hatching, feeding is done twice daily at fixed times: once between 8:00-9:00 AM (50-70% of the total daily feed) and once between 6:00-7:00 PM (30-50% of the total daily feed). Each feeding session lasts 1.0-1.5 hours. During the juvenile stage I of long-snout catfish fry, which is 8-20 days after hatching, the stocking density is 50,000-80,000 fish / acre. During the second juvenile stage of long-snout catfish fry, which is 21-30 days after hatching, the stocking density is 20,000-30,000 fish / acre. For juvenile fish in stages I and II, feeding should be done three times a day at set times: once from 08:00 to 09:00 in the morning, accounting for 50-70% of the total daily feed; once from 18:00 to 19:00 in the afternoon, accounting for 15-25% of the total daily feed; and once from 19:00 to 20:00 in the evening, accounting for 15-25% of the total daily feed. Each feeding session should last for 1.0-1.5 hours.

[0014] Furthermore, the fry of the long-snout catfish are obtained by the following method: long-snout catfish sperm cells and long-snout catfish egg cells are mixed to form fertilized eggs, which are then poured into the hatching pond; the fertilized eggs are scooped up from the hatching pond using a net, allowing them to attach to the net; the net is suspended in the hatching pond, ensuring that all fertilized eggs are below the water surface; the dissolved oxygen in the water is maintained at 6-8 mg / L, the water transparency at 25-30 cm, the pH at 7.0-8.5, the ammonia nitrogen at <0.02 mg / L, and the nitrite at <0.01 mg / L; after the fry hatch, they are temporarily raised in the hatching pond for 1-2 days, and then transferred to the nursery pond.

[0015] Furthermore, prior to the seedling cultivation step, artificial insemination and incubation steps are set up: Long-snout catfish sperm cells and long-snout catfish egg cells are mixed to form fertilized eggs, which are then poured into the hatching pond; the fertilized eggs are scooped up from the hatching pond using a net, allowing them to attach to the net; the net is suspended in the hatching pond, ensuring all fertilized eggs are below the water surface; the dissolved oxygen in the water is maintained at 6-8 mg / L, water transparency at 25-30 cm, pH at 7.0-8.5, ammonia nitrogen <0.02 mg / L, and nitrite <0.01 mg / L; after the fry hatch, they are temporarily raised in the hatching pond for 1-2 days, and then transferred to the seedling pond. The hatching tank is prepared as follows: Soak the drained hatching tank in oxalic acid solution, then disinfect it with chlorine dioxide; then fill it with clean water, maintaining a water level of 1.2-1.5m, a temperature of 24-26℃, dissolved oxygen ≥5mg / L, and pH 7.0-8.5; the area of ​​the hatching tank is 3-5m². 2 And a rope is hung horizontally above the hatching pool to suspend the netting.

[0016] Furthermore, before the artificial insemination and incubation steps, there is a parent fish spawning induction step: from mid-to-late April to early June, male and female parent fish that are in good reproductive condition are transferred to the spawning induction tank. The female parent fish were first injected with a luteinizing hormone-releasing hormone analogue, followed by a mixture of luteinizing hormone-releasing hormone analogue, human chorionic gonadotropin, and dioxin. Male parent fish were injected with a mixture of luteinizing hormone-releasing hormone analogue, human chorionic gonadotropin, and dioxin; 16-24 hours after injection, check the maturation of the parent fish and extract the egg cells and sperm cells respectively.

[0017] Furthermore, before the artificial insemination and incubation steps, there is a parent fish spawning induction step: from mid-to-late April to early June, male and female parent fish that are in good reproductive condition are transferred to the spawning induction tank. The female parent fish were first injected with a luteinizing hormone-releasing hormone analogue, followed by a mixture of luteinizing hormone-releasing hormone analogue, human chorionic gonadotropin, and dioxin. Male parent fish were injected with a mixture of luteinizing hormone-releasing hormone analogue, human chorionic gonadotropin, and dioxin; 16-24 hours after injection, check the maturation of the parent fish and extract the egg cells and sperm cells respectively.

[0018] Furthermore, for female parent fish, the ratio of luteinizing hormone-releasing hormone analogue, human chorionic gonadotropin and dioxin injected per kilogram of fish body is 2.4-4 μg: 500-800 IU: 2-4 mg; For male parent fish, the ratio of luteinizing hormone-releasing hormone analogue, human chorionic gonadotropin and dioxin injected per kilogram of fish body is 1.5–2.5 μg: 250–400 IU: 1–2 mg.

[0019] Furthermore, prior to the broodstock spawning induction process, there is a broodstock rearing process: the broodstock rearing process begins 1-2 months before the long-snout catfish breeding season; the long-snout catfish breeding season is from late April to early June. The parent fish are placed in the parent rearing pond for breeding; the adult fish feed is a basic fish feed with added nutritional fortifiers. The protein content of the basic fish feed is 40%-45%, and the particle size is 4.0-6.0mm; the nutritional fortifiers include: fish oil at a content of 5%~6%, vitamin E at a content of 150-250mg / kg, and choline chloride at a content of 450-550mg / kg. During the breeding process, feed the parent fish as follows: When the water temperature is ≥10℃, the daily feeding amount is 1.5-2% of the body weight of the parent fish, divided into 1-2 feedings per day; when the water temperature is <10℃, the daily feeding amount is 0.75%-1% of the body weight of the parent fish, fed twice per day; the feeding amount is the sum of the mass of adult fish feed and live bait; live bait includes at least one of small fish, snail and clam meat, and earthworms; the mass ratio of adult fish feed to live bait is 5-7:3-5; The parent stock rearing pond is prepared as follows: remove the silt and debris from the drained parent stock rearing pond, and then disinfect the rearing pond with chlorine dioxide; the next day, inject aquaculture water into the rearing pond, and then sprinkle soybean milk, a dispersion of bacterial and algal nutrient paste and a dispersion of algal polypeptide into the pond.

[0020] In summary, the technical principle of this invention is as follows: Based on the biological characteristics of the long-snout catfish at different life stages, a fully adapted artificial breeding system was constructed. In the broodstock rearing stage, customized high-protein feed was used, combined with sludge removal and disinfection of the rearing ponds and measures for controlling bacteria and algae growth. Feeding strategies were adjusted according to water temperature changes, while maintaining a stable aquatic environment to provide suitable conditions for broodstock reproductive development. In the controlled hatching stage, the hatching ponds were pretreated to eliminate pathogen residues, maintaining suitable water temperature and depth. Fertilized eggs were placed in a suspended manner to prevent mold growth. Water quality parameters were strictly controlled, and a reasonable ratio of male to female broodstock was used to ensure fertilization effectiveness. During the segmented fry rearing process, feeding was stopped when the fry were first introduced into the rearing ponds to allow them to adapt to the environment. After adaptation, automatic feeding equipment was used, and the feed form was adjusted according to the fry's growth. Nighttime auxiliary lighting was used to enhance feeding. The rearing ponds were pretreated according to the standards for broodstock rearing ponds, and regular bacteria and algae control and partial water changes were performed to maintain suitable water transparency and provide a stable environment for fry growth.

[0021] The beneficial effects of this technical solution are as follows: (1) Improve breeding efficiency: Improve the physical condition and reproductive performance of parents through nutrition and environmental optimization during parent breeding; improve the synchronicity of maturation and gamete quality through precise induced labor programs; reduce embryo development problems through controllable incubation environment regulation, and comprehensively improve the overall breeding success rate.

[0022] (2) Ensure seedling quality: segmented seedling adaptation period management, feed adjustment and light source assistance improve the uniformity of seedling feeding; a stable seedling environment reduces growth stress, ensures the consistency of seedling specifications, and at the same time retains the excellent varietal traits of long-snout catfish to meet the needs of subsequent breeding and processing.

[0023] (3) Adapt to large-scale production: Clarify the operation logic and core control direction of each link, unify technical standards, form a replicable system for the whole process from parent breeding to seedling release, reduce the dependence on technology, facilitate the mass production of seedlings, and meet the seedling needs of large-scale breeding.

[0024] (4) Reduced costs and environmental protection: Precise feeding strategies reduce feed waste, stable breeding environment reduces the probability of disease occurrence and reduces drug use costs; low-residue disinfection methods and bacterial and algal regulation technology reduce the impact of breeding activities on the surrounding water environment, which is in line with the development direction of green breeding. Attached Figure Description

[0025] Figure 1 This is a front view of the feeding mechanism in Example 1.

[0026] Figure 2 This is a side view of the feeding mechanism in Example 1.

[0027] The specific reference numerals in the attached figures are as follows: Shade canopy longitudinal support rod 1, water inlet pipe 2, support foot 3, water surface 4, water inlet 5, feeder 6, light source 7, shade canopy top support rod 8, water outlet pipe 9, water outlet 10. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. Unless otherwise specified, the technical means used in the following embodiments and experimental examples are conventional means well known to those skilled in the art, and the materials and reagents used can all be obtained commercially.

[0029] Example 1 A highly efficient and large-scale artificial breeding method for *Catfish simonii* includes the following steps performed sequentially: S1: Breeding of parent fish (1) Time selection Based on the breeding season of the long-snout catfish (usually from April to June in the Yangtze River basin, with a water temperature of 20-25℃), the selection of parent fish should begin 1-2 months in advance, allowing time for temporary rearing and intensive cultivation.

[0030] (2) Selection of parent fish The male-to-female ratio of parent fish should be 3-5:1. If 100 spawning pairs are needed (with 100 females ultimately laying eggs normally), 150 females and 30-50 males are required. In addition to the parent fish mentioned above, 10%-20% of the parent fish should be prepared as backup. That is, backup females: 150 × (10%-20%) = 15-30; backup males: 30-50 × (10%-20%) = 3-10.

[0031] Selection criteria for parent fish: Female fish: 3-5 years old, weighing 2.5-5 kg.

[0032] Male fish: 3-5 years old, weighing 3-6 kg.

[0033] Physical standards: The body is well-proportioned and free from deformities (such as spinal curvature, tail fin defects, etc.). The spines of the dorsal and pectoral fins are well-developed and undamaged. The body surface has a good luster, with the back being grayish-black or grayish-brown and the abdomen being white or grayish-white, without any abnormal pigmentation or fading patches. Mucus secretion is normal and there is no shedding or parasite attachment.

[0034] (3) Conditions of the parent stock rearing pond Cultivation is carried out in cement ponds with an area of ​​1.0-2.0 mu (approximately 0.06-0.067 hectares), with a water depth of over 1.8m. Before stocking, the pond water is drained, and the bottom silt and other debris are thoroughly removed using a high-pressure water gun. Then, the entire pond is disinfected by spraying chlorine dioxide, using 360-500g of chlorine dioxide per mu (prepared to an appropriate concentration for even application, based on solute) to kill pathogens and algae. The chlorine dioxide is applied as a solution, prepared as follows: 0.5kg of powder containing 8% chlorine dioxide is added to a plastic container pre-filled with 10kg of water and stirred thoroughly. After standing for 10 minutes, it is diluted to 50-80kg, resulting in a chlorine dioxide solution concentration of 500-800ppm.

[0035] After disinfection, the next day, fill the fishpond with aquaculture water. This water should be from the breeding grounds, filtered through a 60-80 mesh screen (to prevent wild fish, small shrimp, eggs, and harmful insects from entering the pond). The water quality must meet the following conditions: dissolved oxygen ≥ 5 mg / L, pH 6.5-8.5, ammonia nitrogen ≤ 0.2 mg / L, nitrite ≤ 0.1 mg / L, sulfide ≤ 0.1 mg / L, and transparency 30-40 cm. After adding water, sprinkle soybean milk, algae and bacterial nutrient paste dispersion, and algae-derived polypeptide dispersion onto the pond surface, ensuring even coverage. The soy milk specifically refers to soybean milk, prepared as follows: Soak soybeans for 10-12 hours in advance at a water-to-soybean volume ratio of 2-3:1 to obtain soaked soybeans; when grinding, use a common multi-functional grinder with a power of 1000-2000W, and grind the soaked soybeans together with water at a 2:1 volume ratio in a preheated machine. The resulting solid-liquid mixture is the soy milk applied to the water surface in this solution. The dosage of soy milk is 2.5-5 kg ​​of soybean milk per mu per meter per day for 5 consecutive days. The commercial name of the algae and bacteria nutritional paste is Algae and Bacteria Nutritional Paste II, purchased from Wuhan Agricultural University Baokang Biotechnology Co., Ltd., and its main components include algae strains, beneficial bacteria, algae activating factors, and trace elements. Use 100-150 grams (preferably 120 grams) of algae nutrient paste per mu (unit of land area) per application, only on the day of water addition. Prepare an aqueous solution (algae nutrient paste dispersion) with a concentration of 4-6 g / L and apply it to the water surface. Algae-derived polypeptides are purchased from Wuhan Agricultural University Baokang Biotechnology Co., Ltd., and their main components include various amino acids, trace elements, organic proteins, and fertilizing bacteria. Use 1.0-1.5 kg (preferably 1.2 kg) of algae-derived polypeptides per mu (unit of land area) per application, once every 5-7 days during the aquaculture process. Prepare an aqueous solution (algae-derived polypeptide dispersion) with a concentration of 40-60 g / L and apply it to the water surface.

[0036] Two to three days after the first application of soybean milk, algal nutrient paste dispersion, or algal polypeptide dispersion (also known as fertilization), inoculate the pond with rotifers, artichoke nauplii, or other suitable live feed. Rotifers are small zooplankton, and artichoke nauplii are newly hatched larvae of artichokes, making them one of the most commonly used live feeds in aquaculture. Rotifers and artichoke nauplii are conventional live feeds available through existing technology and can be obtained commercially, so they will not be elaborated on here. Taking rotifers as an example, the specific application method is as follows: inoculate 100-200g of rotifers per acre per meter. One to two days before stocking the parent fish, take samples of pond water for microscopic examination to ensure that the rotifer density reaches 10-20 individuals / mL and the cladoceran density reaches 1-3 individuals / mL. These are considered suitable feed densities. Cladocera, belonging to the phylum Arthropoda, class Crustacea, and order Cladocera, are small planktonic crustaceans (such as water fleas). They are tiny, feed on phytoplankton and organic detritus, and are widely distributed in freshwater bodies, serving as a common natural live food source for aquaculture. In aquaculture water, algae can be cultivated through fertilization (using soybean milk, algal nutrient paste dispersion, or algal polypeptide dispersion), which in turn allows cladocerans to proliferate naturally (due to dormant eggs naturally present in the bottom sediment and water source), forming a natural food source without the need for pre-introduction like rotifers. Furthermore, the water transparency should be controlled at 25-35 cm. Once the water transparency and plankton density meet the standards, broodstock fish should be released on a sunny morning. One day before releasing the broodstock fish, a vitamin stress reliever (0.5 kg per acre per meter) should be applied to the entire pond to reduce stress on the fish. Vitamin Stress Relief is a commonly used compound preparation in aquaculture and livestock farming for its anti-stress, nutritional supplementation, and body stabilization effects. Its core ingredient is highly stable Vitamin C, combined with various vitamins and functional components, specifically designed to address environmental and operational stress. Its main components are coated Vitamin C, Vitamin E, B vitamins, and plant polysaccharides, which can effectively alleviate stress responses in farmed animals, supplement nutrition, enhance immunity, and improve survival rates. It is commercially available and will not be discussed further here.

[0037] (4) Management of parent fish stocking The stocking density of broodstock is controlled at 100-150 fish / acre. To avoid frequent chasing and harassment of females by male fish, and to reduce fish injury and stress, male and female broodstock are raised in separate ponds. The size difference of broodstock in the same pond should not exceed 10-15%. When transferring broodstock, a semi-open, soft nylon net (90cm × (30cm + 30cm)) is used. The selected broodstock are introduced into the open net and lifted directly from the water, along with the net, into a transfer tank (70-80cm × 50-60cm × 50-55cm). The transfer tank is pre-filled with 1 / 2-2 / 3 of the culture water and aerated, with 3-5‰ sodium chloride and 1-2ppm vitamin C added to the water. After the broodstock arrive at the rearing pond, the net is tightened and the broodstock are lifted and placed into the rearing pond (tightening the net prevents the fish from struggling and getting injured). Each semi-open, soft nylon net contains one fish, which can effectively prevent mechanical damage to the fish and subsequent infection. Preferably, when placing the parent fish in the rearing pond, the entire pond is sprayed with a 10% povidone-iodine solution for simple disinfection (540-900 mL / acre). The above-mentioned method of transporting adult fish is a conventional method in the existing technology and will not be described in detail here.

[0038] After the broodstock fish are introduced into the rearing pond, routine maintenance is required: maintain a slight water flow (water flow speed controlled at 0.1-0.2 m / s to stimulate the metabolism of the broodstock), change 10%-15% of the water daily (replacing with fresh water as described above), and maintain dissolved oxygen and feed density. Regularly test the water quality, maintaining dissolved oxygen ≥5 mg / L, pH 6.5-8.5, ammonia nitrogen ≤0.2 mg / L, nitrite ≤0.1 mg / L, sulfide ≤0.1 mg / L, and transparency 25-35 cm.

[0039] (5) Nutritional fortification program The specific details of the fish feed are as follows: A high-protein basic fish feed is used (preferably, feed No. 4 or No. 5 from Sichuan Zhonglian Chuang Biotechnology Co., Ltd.; feed No. 4 has a particle diameter of approximately 3.0-5.0 mm; feed No. 5 has a particle diameter of approximately 5.0-7.0 mm; and the protein content of the feed is 40%-45%). Preferably, the protein in the basic fish feed is mainly composed of high-quality fishmeal, soybean meal, and silkworm pupa powder. Fish oil (5-6% by weight, preferably 5.5%), vitamin E (150-250 mg / kg, preferably 200 mg / kg), and choline chloride (450-550 mg / kg, preferably 500 mg / kg) are added to the basic fish feed. This scheme uses a high-protein basic fish feed, as the protein content of ordinary fish feed is typically 35%-40%. Furthermore, fish oil is added to the fish feed in this scheme to increase DHA / EPA supply. In addition, vitamin E and choline chloride are added to prevent fatty liver. At the same time, fresh live bait (such as small fish, snail and clam meat, earthworms, etc.) should be added to the daily diet, accounting for about 30%-50%, and chopped up before feeding to improve palatability.

[0040] The daily feed amount (basic fish feed + additives + live bait) should be 1.5-2% of the broodstock's body weight, divided into 1-2 feedings per day. The total daily feed amount needs to be adjusted according to the water temperature. When the water temperature is ≥10℃, feed normally as described above. When the water temperature is <10℃, the daily feed amount for the broodstock should be 0.75%-1% of the broodstock's body weight, fed twice a day.

[0041] S2: Inducing spawning in parent fish: (1) Controlling the timing of labor induction Following the S1 method, broodstock fish are cultured in rearing ponds, and spawning is induced after approximately 2-3 months. In the Yangtze River basin, the breeding season is from mid-April to early June (peak in May), therefore, spawning induction should be performed during this period. During this time, the broodstock's gonads develop to stage IV (the abdomen is soft and swollen, and eggs or sperm may flow out upon gentle pressure). During this timeframe, when the water temperature in the open-air rearing ponds is stable at 22-25℃, the selection of broodstock for spawning induction should commence. Spawning induction should be performed on consecutive sunny days with light winds, avoiding heavy rain, hot and humid low-pressure weather, or sharp temperature drops (low pressure leads to decreased dissolved oxygen, affecting spawning in the broodstock).

[0042] The selection criteria for broodstock fish are based on the seine net method used to select broodstock from the rearing pond, and the following conditions must be met: Female characteristics: The genital process is short and blunt (0.5±0.1cm), with a rounded and pinkish end. The abdomen is enlarged and soft. When the abdomen is supine, the outline of the ovary is clearly visible. The abdomen is elastic and without hard lumps when gently pressed. Male characteristics: The genital protuberance is long and pointed (1.0cm-2cm), with a reddish tip. When the abdomen is squeezed, a small amount of milky white semen can be seen flowing out, which disperses upon entering the water.

[0043] (2) Preparation of spawning tank for parent fish An indoor labor induced labor tank, with an area of ​​3-5 square meters, is generally chosen. 2 Beforehand, soak the scale on the pool walls with disinfectant oxalic acid (concentration of 10-15 mg / L), and then disinfect with bleaching powder (chlorine dioxide concentration of 0.1-0.3 mg / L). After disinfection, fill the spawning tank with fresh aquaculture water, maintaining a water level of 1.2-1.5 m, a water temperature of 24-26℃, and ensuring clean water quality (maintaining dissolved oxygen ≥5 mg / L and pH 7.0-8.5).

[0044] Selected broodstock fish are guided into a semi-open, soft nylon net (90cm x (30cm + 30cm)). Immediately transfer them to a pre-prepared transfer tank (70-80cm x 50-60cm x 50-55cm). The tank water should have dissolved oxygen ≥5mg / L, pH 7.0-8.5, and a water level of 30-40cm. Add 2ppm of Vitamin C two hours before transport to reduce stress. Transport males and females separately, with each transfer tank holding 2-4 broodstock fish. Upon arrival at the spawning tank, tighten the net to prevent the broodstock from struggling and slowly place them into the pre-prepared spawning tank.

[0045] (3) Induction of labor This protocol uses a combination of luteinizing hormone-releasing hormone analogue (Luteinizing Hormone-Releasing Hormone A2, LHRH-A2, Veterinary Drug Approval No. 110912655) + human chorionic gonadotropin (HCG, Veterinary Drug Approval No. 110911771) + domperidone (DOM, also known as domperidone, Veterinary Drug Approval No. 110912944) to synergistically improve the oxytocin induced rate and egg quality.

[0046] The specific labor induction plan is as follows: The parent fish are injected with medication 1-2 days after being placed in the spawning tank. For female fish, the injection is divided into two doses. The first dose is LHRH-A2, at a dose of 0.6-1 μg per kilogram of fish (0.6-1 μg / kg, preferably 0.8 μg / kg). The second dose is given 10-12 hours later, using a mixture of "LHRH-A2 2.4-4 μg + HCG 500-800 IU + DOM 2-4 mg per kilogram of female fish," i.e., LHRH-A2 2.4-4 μg / kg, HCG 500-800 IU / kg, DOM 2-4 mg / kg (preferably: LHRH-A2 3 μg / kg, HCG 600 IU / kg, DOM 3 mg / kg). The three drugs are not injected separately, but are mixed and injected at once. After measuring the appropriate amount of medication, dissolve it separately in water for injection or physiological saline. Mix the dissolved solutions according to the dosage, shake well, and then use. For male fish, administer only one injection of the spawning-inducing composition. The formula for the spawning-inducing composition is "LHRH-A2 1.5-2.5μg + HCG 250-400IU + DOM 1-2mg" per kilogram of fish, i.e., the dosage is LHRH-A2 1.5-2.5μg / kg, HCG 250-400IU / kg, DOM 1-2mg / kg (preferably: LHRH-A2 2μg / kg, HCG 300IU / kg, DOM 1.5mg / kg). The male fish is injected simultaneously with the second injection into the female fish. It is important to note that the injection volume for each parent fish is generally 0.5-2.0mL to avoid tissue damage due to excessive fluid. Generally, the pectoral fin base is selected for intraperitoneal injection. When injecting into the abdominal cavity, the needle is at a 45° angle to the fish body, and the insertion depth is about 0.5-1.0 cm.

[0047] After the injection, check the maturation of the parent fish 16-24 hours later. If the female fish has a swollen and soft abdomen, a red and swollen genital opening, and obvious ovarian movement, and if the male fish releases milky white semen when its abdomen is gently pressed and the semen disperses quickly upon contact with water, then artificial insemination can be prepared.

[0048] S3: Artificial insemination and incubation (1) Preparation of the hatchery The preparation of incubation tanks and oxytocin tanks is basically the same; generally, indoor incubation tanks with an area of ​​3-5 square meters are selected. 2 The oxalic acid soaking and bleaching powder disinfection processes are the same as those in the spawning tank. After disinfection, clean water is added to the hatching tank, with the water level at 1.2-1.5m, the water temperature controlled between 24.0-26.0℃, and the pH at 7.0-8.5. Two ropes are hung horizontally in the middle of the tank, with a spacing of 65-70cm between them, to facilitate hanging the fish eggs on the attached netting.

[0049] (2) Artificial insemination Egg cells and sperm cells were obtained from matured female and male fish using conventional methods (e.g., gently pressing the abdomen of the fish). After extraction, the sperm cells were placed in a dry container and diluted with sperm preservation solution at a ratio of 1:5-8. The sperm preservation solution was prepared as follows: 7.5-8g NaCl, 0.2-0.4g KCl, 0.14-0.2g CaCl2, 0.2g MgSO4·7H2O, 0.06g KH2PO4, 0.35g NaHCO3, and C6H2O. 12 Add 3g of O61 to distilled water, bring the volume to 1L, and adjust the pH to 6.5-7.0. Preferably, 1L of sperm preservation solution contains 8g NaCl, 0.3g KCl, 0.16g CaCl2, 0.2g MgSO4·7H2O, 0.06g KH2PO4, 0.35g NaHCO3, and C6H2PO4. 12 O62g, pH 7.0. After pretreatment, the oocytes are placed in a dry container. Diluted sperm cells are quickly poured into the fish eggs and gently mixed with a feather to form fertilized eggs, which are then evenly poured into the hatching tank. The ratio is 12-17mL of diluted semen per 100,000 mature oocytes. This ratio ensures sufficient sperm-egg fusion, balancing fertilization rate and semen utilization. Oocyte counting method: The total number of oocytes is estimated by "sample weight percentage × total weight". This method is suitable for scenarios where the oocytes are uniform and free of large amounts of impurities, with an error rate of approximately 5%-10%. Specific procedures are as follows: Oocyte pretreatment: Oocytes obtained by artificial spawning from long-snout catfish were rinsed with physiological saline to remove impurities and then dried with filter paper (to avoid moisture affecting the accuracy of weight). Total weight measurement: Weigh the total weight of the cleaned oocytes using an electronic balance (accuracy 0.01g) (denoted as W, unit g). Sample collection: Randomly select 3 parallel samples from the total oocytes, each weighing 5-10g (denoted as w1, w2, w3 to ensure the representativeness of the samples), and calculate the average weight of the samples; Sample counting: Place each sample in a culture dish, disperse the oocytes with a dropper or toothpick, count each oocyte individually (denoted as n1, n2, n3), and take the average value; Total oocyte count calculation: Total oocyte count (N) = (Total weight W / Sample average weight) × Sample average oocyte count).

[0050] Using a pre-prepared net (65cm x 33cm, 40-60 mesh), evenly scoop up the fish eggs and attach them to the net. Suspend the net in the hatching pond, ensuring all fertilized eggs are below the water surface. (Per 1m...) 3 Release 200,000 to 300,000 fertilized eggs into the water to avoid excessive density that could lead to oxygen deficiency.

[0051] (3) Incubation During the hatching period of fertilized eggs, maintain dissolved oxygen in the water at ≥5 mg / L, ideally between 6-8 mg / L. Aerate the water using a gentle flow or aeration, avoiding strong currents that could scatter the fertilized eggs. Regularly monitor dissolved oxygen, especially during the later stages of hatching (embryo hatching), when the fry's oxygen consumption increases, requiring enhanced aeration. Maintain water transparency of 25-30 cm, ensuring clean water quality and avoiding turbidity or pollution. A pH of 7.0-8.5, with slightly alkaline to neutral water, is more conducive to hatching. Ammonia nitrogen <0.02 mg / L, nitrite <0.01 mg / L, and maintain a gentle flow of water. After hatching, temporarily raise the fry in the hatching tank until they reach the larval stage, then transfer them to the nursery tank. Handle the fry with water during transfer to avoid injury; the temperature difference between the hatching and nursery tanks should not exceed 2℃.

[0052] S4: Large-scale fish fry cultivation (seedling cultivation steps) (1) Preparation of seedling beds The preparation of the seedling bed is basically the same as that of the parent stock rearing bed, and the specific process is as follows: Cultivation was carried out in cement ponds with an area of ​​1.0-2.0 mu (approximately 0.06-0.067 hectares), with a water depth of 1.8m or more (1.8m was used in subsequent experiments). Before transferring the fry, the pond water was drained, and the bottom silt and other debris were thoroughly removed using a high-pressure water gun. Then, chlorine dioxide was sprayed throughout the pond for disinfection. 360-500g of chlorine dioxide per mu (based on solute, prepared into a solution of appropriate concentration for easy even spraying; 400g is preferred) was used to kill pathogens and algae. Chlorine dioxide was applied in the form of a chlorine dioxide solution, which was prepared as follows: 0.5kg of powder containing 8% chlorine dioxide was added to a plastic container pre-filled with 10kg of water and stirred thoroughly. After standing for 10 minutes, it was diluted to 50-80kg, i.e., the concentration of the chlorine dioxide solution was 500-800ppm; 650ppm is preferred.

[0053] After disinfection, the next day, aquaculture water is added to the fishpond. This water is from the breeding grounds and has been filtered through a 60-80 mesh screen, meeting the following conditions: dissolved oxygen ≥ 5 mg / L, pH 6.5-8.5, ammonia nitrogen ≤ 0.2 mg / L, nitrite ≤ 0.1 mg / L, sulfide ≤ 0.1 mg / L, and transparency 30-40 cm. After adding water, soybean milk, algae and bacterial nutrient paste dispersion, and algae-derived polypeptide dispersion are sprinkled into the pond, ensuring even coverage of the entire surface. The soy milk specifically refers to soybean milk, prepared as follows: Soak soybeans for 10-12 hours (preferably 2.5:1, 11 hours) at a water-to-soybean volume ratio of 2-3:1 to obtain soaked soybeans. When grinding, use a standard multi-functional grinder with a power of 1000-2000W, and grind the soaked soybeans and water together in a preheated machine at a water-to-soybean volume ratio of 2:1. The resulting solid-liquid mixture is the soy milk. The dosage is 2.5-5 kg ​​of soybean milk per mu / meter per day (preferably 4 kg), for 5 consecutive days. The commercial name of the algae and bacteria nutritional paste is Algae and Bacteria Nutritional Paste II, purchased from Wuhan Agricultural University Baokang Biotechnology Co., Ltd. Its main components include algae strains, beneficial bacteria, algae activating factors, and trace elements. Use 100-150 grams (preferably 120 grams) of algae nutrient paste per mu (unit of land area) per application, only on the day of water addition. Prepare an aqueous solution (algae nutrient paste dispersion) with a concentration of 4-6 g / L and apply it to the water surface. Algae-derived polypeptides are purchased from Wuhan Agricultural University Baokang Biotechnology Co., Ltd., and their main components include various amino acids, trace elements, organic proteins, and fertilizing bacteria. Use 1.0-1.5 kg (preferably 1.2 kg) of algae-derived polypeptides per mu (unit of land area) per application, sprinkling it every 5-7 days (preferably 5 days) during the aquaculture process. Prepare an aqueous solution (algae-derived polypeptide dispersion) with a concentration of 40-60 g / L and apply it to the water surface.

[0054] Two to three days (preferably three days) after the first application of soybean milk, algae and bacterial nutrient paste dispersion, or algae-derived polypeptide dispersion (also known as fertilization), inoculate the pond with rotifers, artichoke nauplii, or other suitable live feed. Taking rotifers as an example, the specific application method is explained below. Inoculate 100-200g (preferably 150g) of rotifers per acre per meter, directly providing the first feed for the fish fry. One to two days before stocking the fish fry, take samples of pond water for microscopic examination to ensure that the rotifer density reaches 10-20 individuals / mL (preferably around 15 individuals / mL) and the cladoceran density reaches 1-3 individuals / mL (preferably around 2 individuals / mL). These are considered suitable feed densities. In addition, the water transparency should be controlled at 25-35cm. Once the water transparency and plankton density meet the standards, stock the fish fry on a sunny morning. One day before stocking the fish fry, apply 0.2-1kg of vitamin stress reliever per acre per meter (preferably 0.5kg per acre per meter) to the entire pond to reduce the fish's stress response. Perform routine maintenance on the nursery ponds, maintaining a slight water flow (flow speed controlled at 0.1-0.2 m / s), changing 10-15% of the water daily to maintain dissolved oxygen and feed density. Regularly test the water quality, maintaining dissolved oxygen ≥5 mg / L, pH 6.5-8.5, ammonia nitrogen ≤0.2 mg / L, nitrite ≤0.1 mg / L, sulfide ≤0.1 mg / L, and transparency 25-35 cm.

[0055] (2) Feeding mechanism In addition to preparing the water conditions in the nursery pond, this plan also includes a dedicated fish fry feeding system, details of which can be found here. Figure 1 and Figure 2 Each seedling pond is equipped with its own feeding mechanism, which is located near the edge of the pond for easy daily operation and management.

[0056] The feeding mechanism includes a shade canopy, which is constructed with a support frame covered by a light-blocking cloth. The frame consists of four vertically arranged longitudinal support rods 1 and four rectangular top support rods 8 fixed end-to-end. The longitudinal support rods 1 are fixed below the rectangular top support rods 8. The fixing methods can employ conventional means well-known to those skilled in the art, including but not limited to welding and other fixed connections, as well as bolted or plugged connections for detachable connections. The support rods form a cubic frame structure with dimensions of 1-2m length, 1-1.5m width, and 0.6-1.0m height (preferably 1.5m length, 1.2m width, and 0.8m height). The height of the top support rods 8 from the water surface 4 does not exceed 1.2m (preferably 1.2m) to reduce the overall height of the feeding mechanism and minimize wind load.

[0057] The lower end of the longitudinal support rod 1 of the shade canopy is fixed above the micro-flow water device. The micro-flow water device consists of three outlet pipes 9 and one inlet pipe 2 connected together. The inlet pipe 2 is equipped with an inlet 5 for introducing fresh aquaculture water (or water from the nursery pond can be pumped in). Several outlets 10 are provided on the outlet pipe 9 for discharging fresh water (or water from the nursery pond) into the nursery pond, the main purpose of which is to create a micro-flow water environment. The micro-flow water can create suitable slow-flow conditions for fish fry, while achieving gentle oxygenation and avoiding damage to the fish fry caused by the impact of high-power aerator water flow. Four support feet 3 are fixed at the bottom of the micro-flow water device, and the support feet 3 are inserted into the bottom of the nursery pond for fixation. The above fixing method can be any conventional means well known to those skilled in the art, including but not limited to welding and other fixed connection methods, as well as bolted connections, plug-in connections, and other detachable connection methods.

[0058] The top and four sides of the shade canopy are covered with a light-transmitting cloth with a light transmittance of 70-80% (preferably 75%) using conventional methods. The four sides of the rectangular light-transmitting cloth are fixed to the corresponding longitudinal support rod 1, the top support rod 8, or the water outlet pipe 9. For example, ropes can be threaded through the sides of the light-transmitting cloth and tied to the corresponding rods. The upper part of the light-transmitting cloth suspended on the side of the water inlet 5 is fixed to the top support rod 8. Flexible hooks are used for fixing on the sides and bottom, facilitating easy removal for feeding the feeder 6. A conventional feeder 6 is suspended in the middle of the top of the shade canopy using conventional methods. For example, suspension rods are set on the two diagonals of the quadrilateral support on the top of the shade canopy, with both ends welded and fixed to the quadrilateral support. The intersection of the suspension rods is used to suspend the feeder 6. The feeder 6 has its own light source 7, with the light intensity controlled at 200–400 μmol / m². 2 s (preferably 300 μmol / m 2 (s), the light source 7 is 0.3-0.6m (preferably 0.5m) away from the water surface 4. This light intensity can gently attract zooplankton to gather, assisting the long-snout catfish fry to start feeding on zooplankton; in conjunction with the feeder 6, the fry become familiar with the smell of artificial feed during the initial feeding process, and successfully complete the acclimatization and transition to artificial feed.

[0059] Four areas on the water surface directly below the feeding device are randomly placed with concealment structures to facilitate hiding and feeding for the fish fry. The concealment structures can be honeycomb-shaped metal or cement frames, which provide shelter for the fish fry and are easy to obtain and sturdy.

[0060] (3) Fish fry farming After the fry are released into the nursery ponds, they are cultured according to the characteristics of longsnout catfish fry. The growth of longsnout catfish fry consists of three stages, and the physiological needs of each stage necessitate a gradual transition in nutrition through feeding. Therefore, different feeding methods are used for each of the three stages: Larval stage (body length approximately 1.2-1.8cm, also known as the opening stage): This period lasts 4-7 days after hatching. The yolk sac gradually depletes, the mouth opens, and the fish begins to feed on small zooplankton (such as rotifers and cladoceran larvae). For fry in the larval stage, the stocking density is 100,000-150,000 fry / acre (120,000 fry / acre recommended).

[0061] Four to five days after hatching, the feeder automatically dispenses powdered feed (preferably Tongwei Co., Ltd.'s Kaikoule No. 0 powdered feed, hereinafter referred to as powdered feed; with a protein content of 46-48%) into the water. The powdered feed must be sieved through a screen of at least 80 mesh, preferably through a 100-mesh screen. Feeding is conducted 24 hours a day with the lights on. During this stage, the fry are fed small zooplankton (rotifers, small cladocerans, etc.) mixed with the powdered feed to familiarize them with the taste. Feeding of the powdered feed during this stage is primarily done in small, continuous amounts, i.e., continuously in small amounts 24 hours a day. The fry primarily feed during the day, with the feed amount accounting for 5-8% of their body weight (preferably 7%).

[0062] Six to seven days after hatching, as the fry gradually adapt, feeding should be adjusted to twice-daily scheduled feeding: once between 8:00 and 9:00 AM, accounting for 50-70% (preferably 60%) of the total daily feed; and once between 6:00 and 7:00 PM, accounting for 30-50% (preferably 40%) of the total daily feed. Each feeding session should last 1.0 to 1.5 hours (preferably 1.2 hours). The feed amount should still be within the range of 5-8% (preferably 7%) of the fry's body weight.

[0063] Juvenile stage I (body length approximately 1.8-3.0 cm): This period is 8-20 days after hatching, when the yolk sac has completely disappeared and the digestive system has matured (the intestines are tortuous and the liver and pancreas are fully functional). For fry in stage I, the stocking density is 50,000-80,000 fry / acre (60,000 fry / acre recommended).

[0064] Longsnout catfish fry are acclimatized to a new diet starting 8 days after hatching, using a 3-5 day gradual transition program (preferably 5 days). They are switched from powdered feed to Tongwei Co., Ltd.'s Kaikoule No. 1 microparticle feed (preferably the finest crushed feed with a protein content of 46%-48%, sieved through a 40-mesh sieve or better, a 60-mesh sieve). On the first day, the fry are fed 90%-95% powdered feed and 5%-10% pelleted feed. The proportion of pelleted feed is then increased evenly each day until days 3-5 when the fry are fed 100% pelleted feed. During this period, the powdered and pelleted feeds are thoroughly mixed and fed in small amounts frequently to smoothly complete the transition from powdered to pelleted feed. The transition is completed 10-12 days after hatching, and subsequent rearing up to 20 days after hatching uses 100% pelleted feed.

[0065] During this stage (8-20 days after hatching), a light-on feeding method is adopted, divided into three times a day: once from 8:00-9:00 AM, accounting for 50-70% (preferably 60%) of the total daily feed; once from 6:00-7:00 PM, accounting for 15-25% (preferably 20%) of the total daily feed; and once from 7:00-8:00 PM, accounting for 15-25% (preferably 20%) of the total daily feed. The duration of each feeding session should be controlled between 1.0 and 1.5 hours (preferably 1.2 hours). During the 8-20 days after the fish fry hatch, the percentage of total feed intake to the fish fry's body weight is gradually increased from 5%-8% (preferably 7%) to 8%-12% (preferably 10%) over a period of 12 days, with a total increase of 3-7%, and an average daily increase of 0.25-0.58%, ensuring that the feed intake increases steadily and smoothly as the fish fry grow.

[0066] Juvenile Stage II (body length 3.0-5.0cm): This period is from 20 to 30 days after hatching. For fry in stage II, the stocking density is 20,000-30,000 fish per mu (25,000 fish per mu is recommended).

[0067] From 21 days after hatching, longsnout catfish fry undergo a 3-5 day gradual transition program, transitioning from pelleted feed to larger-diameter pelleted feed. The larger-diameter pelleted feed is also the longsnout catfish-specific pelleted feed produced by Tongwei Co., Ltd. (selecting No. 1 pellets with a particle size of 1-2mm and a protein content of 40%-48%). The 3-5 day gradual transition program is the same as the transition program from powdered feed to pelleted feed described earlier, and will not be repeated here. During this stage, a feeding method with lights on is used, three times a day (specific feeding times are the same as in fry stage I). In fry stage II, the percentage of pelleted feed to body weight is 10-15% (preferably 13%).

[0068] Fish fry were cultured until 30 days after hatching (end of juvenile stage II). The survival rate of the fish fry was calculated as: (number of fish fry at the end of culture / number of fish fry initially transferred to the nursery pond) × 100%. Using the fry rearing scheme of this embodiment, the survival rate of fish fry can be maintained at 80-90%, greatly improving the success rate and efficiency of fry rearing. More specifically, following the optimal method of "S4: Large-scale fry rearing (fry rearing steps)," fish fry are raised from the larval stage until the end of juvenile stage II (4 days to 30 days after hatching), and the survival rate of fish fry can reach about 90%.

[0069] Comparative Example 1 (1) Use Artemia ( Artemia salina Seedling cultivation plan and its effects This comparative example uses brine shrimp as the initial feed, a method that is relatively efficient among existing feed conversion techniques. However, its disadvantages include the high cost of brine shrimp and the large overall investment, making it unsuitable for large-scale application. The specific operation method is as follows: This comparative example uses the optimal method of Example 1 to raise fish fry, which yields a large quantity of fry for subsequent raising operations. In this comparative example, the preparation of the rearing pond differs from Example 1; no fertilization with soybean milk or similar substances is performed. A 1.0-acre cement pond is used for rearing, with a water depth maintained above 1.8m. Before transferring the fry, the pond is drained and disinfected with chlorine dioxide, as in Example 1. Then, the pond is filled with the same aquaculture water as in Example 1. After adding water, no more soybean milk, algae nutrient paste dispersion, or algae-derived polypeptide dispersion is added (rotifer inoculation is still performed as in Example 1). Because no fertilization is performed, rotifer density testing is not conducted before releasing the fry. The fry are released on a sunny morning. One day before releasing the fry, a vitamin stress reliever (0.5 kg per acre per meter) is applied to the entire pond. Routine maintenance of the seedling pond should be performed, maintaining a slight water flow (flow velocity controlled at 0.1-0.2 m / s), with 10-15% of the water changed daily. Water quality should be tested regularly, maintaining dissolved oxygen ≥5 mg / L, pH 6.5-8.5, ammonia nitrogen ≤0.2 mg / L, nitrite ≤0.1 mg / L, sulfide ≤0.1 mg / L, and transparency 30-40 cm. In this comparative example, the feeding mechanism is set up exactly the same as the optimal method in Example 1.

[0070] This comparative example used two feeding methods, as detailed below: Feeding method 1: During the larval stage (4-5 days after hatching), the feeding mechanism automatically and continuously fed the fry powdered feed in minute quantities 24 hours a day, operating exactly as the optimal feeding method for the corresponding stage in Example 1. The difference was that this comparative example did not involve fertilization, so brine shrimp were also fed during this stage, with the amount of brine shrimp being 20% ​​of the powdered feed mass. The brine shrimp were manually applied to the water surface below the feeding mechanism, three times a day: once from 8:00-9:00 AM, accounting for 60% of the total daily brine shrimp feed; and once from 6:00-7:00 PM, accounting for 40% of the total daily brine shrimp feed.

[0071] During the larval stage (6-8 days after hatching), the brine shrimp were introduced in the same manner as above, and the powdered feed was introduced in the same manner as the optimal operation method in Example 1 at the same stage.

[0072] The feeding method for fry stage I and fry stage II is exactly the same as the optimal operation method for the same stage in Example 1. The survival rate of the fry reached 90% when the fry were raised until 30 days after hatching (end of fry stage II).

[0073] Feeding method 2: The difference from feeding method 1 is that powdered feed balls are used instead of powdered feed during the larval and first juvenile stages; all other operations are exactly the same as feeding method 1. Powdered feed balls refer to feed balls formed by mixing powdered feed and water in a 1:1 ratio. It should be noted that the percentage of feed given to the fry's body weight needs to be calculated based on the dry weight of the powdered feed. Using this feeding method, the fry survival rate can reach 90%. Therefore, using brine shrimp as the initial feed does not have special requirements regarding the state of the powdered feed; feeding directly with powdered feed or using powdered feed balls can achieve a relatively ideal fry survival rate. Feeding with feed balls made by mixing powdered feed and water in a 1:1 ratio is less prone to scattering and loss compared to pure powdered feed, resulting in a lower solubility rate. This improves feed utilization, reduces water pollution, maintains water quality stability, and is more in line with the feeding habits of fry, promoting normal growth and development. Larvae have small mouths and weak feeding abilities; powdered feed is too fine and difficult for them to concentrate on. Feed pellets, on the other hand, can slowly dissolve into small particles, forming a continuous and stable food source, which is closer to the natural feeding behavior of larvae and promotes uniform growth. When the survival rate of larvae is similar, powdered feed pellets are preferred when using brine shrimp as the first food. Compared with the preferred method of feeding with powdered feed in Example 1, the feeding method in this comparative example is significantly different. This further illustrates that the technical solution of using soybean milk and other fertilizers to construct a zooplankton community as the first food for larvae has outstanding uniqueness compared to existing conventional technical solutions, and those skilled in the art cannot directly derive the overall operation method of this technical solution from existing conventional techniques.

[0074] (2) Preparation method and cost analysis of Artemia First, pre-treat the Artemia eggs by thawing. Take out two containers (425g / container, totaling 850g) of Artemia eggs and place them at room temperature to thaw naturally for 24 hours, avoiding direct sunlight and violent shaking to ensure even awakening of the eggs and lay the foundation for subsequent hatching. Hatching equipment and consumables include: a 500L hatching tank (with sufficient space to prevent water overflow during aeration), a heater (precise temperature control type), an oxygenation device (including air stones to ensure fine bubbles), a lighting device (adjustable brightness, supporting output above 2000 lux), a pH meter, an electronic scale, iodine-free salt, and sodium bicarbonate (baking soda). Test the temperature control accuracy of the heater and the aeration intensity of the oxygenation device beforehand to ensure stable equipment operation. Rinse the hatching tank thoroughly with clean water; no additional disinfection is required (to avoid residual chemicals affecting the eggs).

[0075] Fill a 500L hatching tank with sufficient clean water (tap water should be left to stand for 24 hours to remove chlorine, or purified water can be used directly) to ensure the water is free of impurities and chlorine residue. Weigh out 7500g (7.5kg) of non-iodized salt at a ratio of 15g of non-iodized salt per liter of water, and slowly pour it into the water while continuously stirring until the salt is completely dissolved, achieving a hatching salinity of 15‰ (optimal concentration). Use a pH meter to test the pH value of the water. If it is below 8.2, add sodium bicarbonate solution, stir well, and test again until the pH stabilizes between 8.2 and 8.3.

[0076] After confirming that the salinity and pH of the hatching water meet the standards, turn on the heater and oxygenation device, adjust the water temperature to 26-28℃, and keep it constant. Add eggs at a density of 850g per 500L of water, evenly scattering the thawed eggs into the water and gently stirring for 3-5 minutes to ensure that the eggs are in full contact with the water and that there is no clumping.

[0077] Turn on the lighting equipment and adjust the brightness to above 2000 lux, maintaining continuous lighting for 24 hours. Maintain continuous high-intensity aeration, using air stones to refine the bubbles, ensuring the water is evenly turbulent with no dead zones, guaranteeing sufficient oxygen for the eggs and larvae and preventing localized oxygen deprivation that could lead to death. During incubation, observe and record the water temperature and pH value every 6 hours. If temperature fluctuations or pH deviations occur, adjust the equipment or add sodium bicarbonate promptly to ensure all parameters consistently meet requirements.

[0078] After 24-28 hours of incubation, when a large number of orange-red nauplius larvae (active and swimming nimbly) are observed in the water, turn off the heating, oxygenation, and lighting equipment, and allow the water in the hatching tank to settle naturally for 10-20 minutes. Once the brine shrimp larvae have fully settled to the bottom of the hatching tank, use a siphon method or directly open the drain valve at the bottom of the tank to slowly drain and collect the larval mixture. Avoid violent shaking during collection to reduce damage to the larvae. After collection, the mixture can be used for feeding or temporary rearing.

[0079] Cost accounting for Artemia was conducted, using 100g of aquaculture-grade eggs as the unit, and analyzing two scenarios based on the 2025 Chengdu market price: individual / small-scale hatching and enterprise-level hatching. For individual / small-scale hatching (described earlier in this section), using self-made equipment and excluding labor costs, the total cost per 100g of eggs still reached 24.7-28.0 yuan. If enterprise-level large-scale hatching is used, due to the high proportion of labor costs, the total cost per 100g of eggs further increases to 45.35-54.25 yuan, with the overall cost significantly higher. Therefore, directly feeding Artemia during fish fry rearing significantly increases production costs, especially in large-scale fry production, where its economic viability is poor, making it difficult to promote and apply as a stable, low-cost starter feed solution.

[0080] This technical solution does not use expensive brine shrimp as initial feed. Instead, it treats the pond with fertilization by evenly spreading soybean milk, algae and bacterial nutrient paste dispersion, and algae-derived polypeptide dispersion (these materials are all relatively inexpensive, costing less than 200 yuan per acre per meter for raising one round of fish fry). After the initial fertilization, rotifers are inoculated into the pond. Once the rotifer density reaches 10-20 individuals / mL and the cladoceran density reaches 1-3 individuals / mL, a stable and sufficient natural live food community is formed, directly providing high-quality initial feed for the fish fry. Compared to feeding brine shrimp, this method offers significant cost advantages: firstly, it eliminates the high costs associated with purchasing and hatching brine shrimp eggs, as well as labor and equipment, avoiding the substantial cost pressures associated with large-scale brine shrimp breeding; secondly, it utilizes inexpensive fertilizing materials such as soybean milk, algae and microbial nutrient paste, and algae-derived peptides to cultivate a natural zooplankton community. This method is low-cost, requires minimal dosage, and is easy to operate, eliminating the need for complex hatching equipment and extensive labor, thus drastically reducing overall breeding costs. It is more suitable for large-scale, intensive aquaculture breeding, and its economic efficiency and practicality far surpass the traditional method relying on brine shrimp. In stark contrast to the high-cost brine shrimp feeding model, this invention employs a technique of applying soybean milk, algae and microbial nutrient paste dispersion, and algae-derived peptide dispersion to the entire pond, and inoculating rotifers to construct a natural zooplankton food community. This approach offers a significant cost advantage during the larval feeding stage. This solution only requires water culture using inexpensive and readily available materials such as soy milk, algae and bacteria nutrient paste, and algae-derived peptides, along with a small amount of rotifer inoculation to form a stable and sufficient initial feed. It eliminates the need to purchase expensive Artemia eggs and saves on a series of additional costs such as hatching and artificial feeding.

[0081] Comparative Example 2 This comparative example uses the optimal method of Example 1 to raise fry, which can yield a large quantity of fry for subsequent raising operations. The raising method in this comparative example is basically the same as "S4: Large-scale fry rearing (raising and cultivating steps)" in Example 1, except that all powdered feed during the larval and juvenile stages is replaced with powdered feed pellets. Powdered feed pellets refer to feed pellets formed by mixing powdered feed with water in a 1:1 ratio. It should be noted that the percentage of feed given to the fry's body weight needs to be calculated based on the dry weight of the powdered feed.

[0082] Using the feeding method described in this comparative example, the fry survival rate was only about 60%. Compared to Example 1, this comparative example only replaced the powdered feed with powdered feed pellets, yet it still resulted in a significant decrease in fry survival rate. However, in conventional fry rearing models using brine shrimp (such as Comparative Example 1), the difference between powdered feed and powdered feed pellets does not significantly affect the fry survival rate. This indicates that the specific initial feed rearing model adopted in this technical solution has specific requirements for the form of powdered feed fed during the larval and juvenile stages, a technical principle that is difficult for those skilled in the art to foresee in the early stages of research and development. Generally, those skilled in the art generally consider powdered feed pellets to be more convenient and prefer this method. However, under the specific rearing conditions of this technical solution, directly feeding larvae and juvenile stages with powdered feed significantly improves the fry survival rate, achieving unexpected technical results.

[0083] Comparative Example 3 This comparative example did not involve fertilization of the nursery pond. The preparation method for the nursery pond was exactly the same as in Comparative Example 1. After the fish fry were put into the nursery pond, two methods were used to feed them: Method 1: Feeding is carried out exactly as described in Example 1 (see “(3) Frying” in Example 1 for details); Method 2: Replace all the powdered feed in Example 1 with powdered feed pellets, and perform the remaining operations exactly the same as in "(3) Frying" of Example 1.

[0084] Using method 1, the survival rate of fish fry was approximately 20%; using method 2, the survival rate was approximately 15%. These experimental data illustrate the importance of fertilization and water treatment. This method involves adding soybean milk, bacterial and algal nutrient paste dispersion, and algal polypeptide dispersion to the nursery pond for fertilization and water treatment, and introducing rotifers in the initial stage to build a zooplankton community as the first food for the fry, which greatly improves the survival rate of the fish fry. Without the above methods, neither using powdered feed pellets nor powdered feed during the fry feeding stage can significantly improve the survival rate of the fish fry.

[0085] Comparative Example 4 This comparative example prepared the fry rearing pond according to the method in Example 1, but did not lay any shade cloth on the feeding mechanism; all other operations were exactly the same as in Example 1. Using this comparative example, the fry survival rate was only about 60%. This demonstrates that setting up a shade structure on the feeding mechanism is one of the key factors in improving the fry rearing success rate.

[0086] Based on the experimental results of Example 1 and Comparative Examples 1-4, the initial feeding and transition to new feeding are crucial stages for the survival of long-snout catfish fry. During the larval stage, this method utilizes fertilized water prepared with soybean milk and other additives, providing abundant natural food, including rotifers and small cladocerans, which are phototactic. When the lights are on, the zooplankton in the pond gather under the lights, allowing the fry, sheltered in the shade, to consume sufficient natural food. Simultaneously, a feeder automatically sprinkles in powdered feed, which adheres to various zooplankton and is ingested by the fry. This allows the fry to consume some artificial feed while initially feeding, thus becoming familiar with its taste. Later, when zooplankton becomes scarce, they will naturally switch to artificial feed. During this period, this method can generally guarantee the survival rate of the fry. In Comparative Example 3, because soybean milk and other additives were not used to fertilize the water in the fry rearing pond, there were insufficient small zooplankton, leading to problems with the fry's initial feeding and ultimately a very low survival rate. In Comparative Example 2, the use of powdered feed pellets led to a decrease in fry survival rate. The inventors analyzed that the reason might be that the powdered feed pellets did not adhere well to zooplankton such as rotifers and small cladocerans, failing to effectively familiarize the fry with the taste of artificial feed (thus inducing the fry to eat artificial feed), which also resulted in a certain survival rate loss. In Comparative Example 4, the lack of a shade structure made it difficult for the fry to concentrate at the feeding area, preventing them from consuming enough natural food and becoming familiar with the taste of artificial feed, resulting in a significant survival rate loss. In Comparative Example 1, because sufficient brine shrimp were fed, the fry's initial feeding and feeding issues were basically guaranteed; however, there was a high cost issue. Whether purchasing finished brine shrimp or hatching them oneself, the cost is high. In addition, when there are enough brine shrimp, the fry will preferentially eat brine shrimp, which will make it difficult to switch to artificial feed later. Therefore, considering the survival rate, cost, and later fry rearing, the scheme in Example 1 is the most suitable.

[0087] Comparative Example 5 The main purpose of fertilization during the rearing stage of long-snout catfish fry is to cultivate suitable natural food (mainly rotifers and small cladocerans) while maintaining water quality and preventing deterioration. This technical solution uses soybean milk, algae and bacterial nutrient paste dispersion, and algae-derived polypeptide dispersion for fertilization. Before establishing this technical solution, various fertilization methods had been tried, as detailed below: Attempt 1: Use fully fermented and decomposed pig manure, cow manure, and chicken manure for fertilization. Taking cow manure as an example, the specific steps are as follows: Mix manure and straw in a 5:1 mass ratio, add EM bacteria as usual, and compost for 15-20 days until the manure is odorless and dark brown. Apply fertilizer 300 kg / mu (approximately 200 kg / acre) 7-10 days before stocking fish fry. Soak woven bags filled with the fermented manure in four evenly spaced corners of the pond to allow for slow fertilizer release. This method provides long-lasting fertilization and results in a high zooplankton population, effectively meeting the initial feed intake of fish fry.

[0088] However, traditional fertilization methods relying primarily on organic fertilizers are unsuitable for cultivating longsnout catfish fry in cement ponds. The aquatic ecology and structure of cement ponds differ significantly from those of earthen ponds, making it difficult to adapt to the fertilization effects of organic fertilizers. Cement ponds have smooth walls and lack natural bottom mud, resulting in a small surface area for microbial attachment. Harmful substances such as ammonia nitrogen, nitrite, and hydrogen sulfide produced during the decomposition of organic fertilizers cannot be effectively degraded, easily exceeding safe levels and causing fish fry poisoning. The decomposition of organic fertilizers in cement ponds consumes a large amount of oxygen. Furthermore, the poor water flow and explosive proliferation of plankton in cement ponds, combined with the oxygen consumption from phytoplankton respiration at night and the decomposition of organic matter, can rapidly cause dissolved oxygen levels to drop below 3 mg / L (the safe dissolved oxygen threshold for longsnout catfish fry is above 5 mg / L), leading to fish surfacing and death. Cement ponds have small water volumes and weak self-purification capabilities. After fertilization with organic fertilizers, the water color easily becomes too concentrated (transparency below 20 cm), and this is difficult to quickly adjust through water changes or bottom modifications. Meanwhile, undecomposed organic fertilizer residue will accumulate at the bottom of the pond, breeding harmful bacteria (such as Vibrio) and increasing the risk of fish fry diseases. Furthermore, this fertilization method is labor-intensive and has high management costs, which does not align with the original intention of refined seedling cultivation in cement ponds. For these reasons, the inventors abandoned the method of using fermented manure for fertilization.

[0089] Attempt 2: Using inorganic fertilizers (such as nitrogen, phosphorus, and potassium) to fertilize water can rapidly cultivate plankton and build high-quality algal and bacterial communities. Apply 1.5-2 kg / mu of urea to the seedling pond. Rice, ammonium bicarbonate 3-5 kg / mu The above-mentioned nitrogen fertilizer can promote the rapid reproduction of phytoplankton; apply 2-3 kg / mu of superphosphate to the seedling pond. Rice, 0.5-1 kg / mu of potassium dihydrogen phosphate The aforementioned phosphate fertilizer is an essential element for algae growth; phosphorus deficiency can lead to difficulties in fertilization and irrigation. Apply 0.5-1 kg / mu of potassium chloride to the seedling pond. The potassium fertilizer mentioned above can enhance the stress resistance of algae and promote photosynthesis.

[0090] However, algae cultivated with inorganic fertilizers are mostly dominated by a single species (such as green algae or diatoms), lacking diversity. Once sudden weather changes (such as heavy rain or temperature drops), drastic pH fluctuations, or nutrient imbalances occur, large numbers of algae will die (i.e., algal bloom collapse), leading to a sudden increase in water transparency and a sharp decrease in dissolved oxygen. Simultaneously, the decomposition of dead algae releases toxins, causing stress and even death in fish fry. Inorganic fertilizers only provide macronutrients such as nitrogen, phosphorus, and potassium, lacking essential micronutrients (such as silicon, calcium, magnesium, and iron) and vitamins necessary for phytoplankton growth. Long-term use of inorganic fertilizers alone can deplete micronutrients in the water, resulting in ineffective fertilization. It may also induce outbreaks of harmful algae (such as cyanobacteria), which have a much higher nitrogen and phosphorus absorption efficiency than beneficial algae, easily becoming the dominant species in a single inorganic nutrient environment. Excessive application of inorganic fertilizers can rapidly increase the concentration of ammonia nitrogen (especially molecular ammonia) in the water, directly poisoning the gill tissue of fish fry and causing respiratory distress. During algal blooms, daytime photosynthesis can raise the water pH above 9.0, scorching the fish fry's body surface and gills. At night, algal respiration consumes oxygen, easily leading to hypoxia and fish surfacing. Long-snout catfish are particularly sensitive to ammonia nitrogen, which can cause death during surfacing. Inorganic fertilizers only act on the upper layers of the water and cannot improve the bottom sediment structure through microbial decomposition like organic fertilizers. Long-term use of inorganic fertilizers in cement ponds results in low organic matter accumulation in the bottom sediment, hindering the colonization of beneficial microorganisms, weakening the water's self-purification capacity, and causing water quality fluctuations. These drawbacks of inorganic fertilizers are fatal to the growth of long-snout catfish. For these reasons, the inventors abandoned the method of using inorganic fertilizers for water fertilization.

[0091] Unlike attempts 1 and 2, in Example 1 of this technical solution, soybean milk, algal and bacterial nutrient paste, and algal-derived peptides are used for fertilization, and a small amount of biological feed (e.g., rotifers) is added to rapidly cultivate small plankton as initial feed for fish fry. This technical solution offers strong water quality control and low disease risk; it is suitable for the entire rearing process of longsnout catfish fry from the initial stage to the juvenile stage. This method is a composite model combining traditional fertilization with modern biological agents, offering advantages such as stratified energy supply, targeted algal cultivation, and stable algal community. It leverages the low cost and easy absorption of soybean milk, while algal nutrient paste and algal-derived peptides rapidly activate water nutrients. Combined with biological feed, it constructs a symbiotic ecological chain of "algae-bacteria-insects," suitable for fertilization and water rearing in the early stages of aquaculture, especially for longsnout catfish fry rearing scenarios where high water stability is required.

[0092] Based on the aquaculture results, the inventors analyzed the reasons for the successful development of this method for fish fry: Soy milk is rich in small-molecule proteins, amino acids, and carbohydrates, which can be directly absorbed and utilized by phytoplankton and beneficial bacteria. Simultaneously, its large-molecule organic matter can be decomposed by microorganisms, slowly releasing nutrients such as nitrogen and phosphorus, avoiding the problems of excessive fertilization and algal blooms caused by relying solely on inorganic fertilizers. The bacterial and algal nutrient paste and algal-derived polypeptides can quickly compensate for the slow nutrient release of soy milk, rapidly increasing water fertility and promoting the explosive growth of beneficial algae such as diatoms and green algae. Beneficial microorganisms can decompose organic pollutants such as uneaten feed and feces in the water, converting them into nutrients usable by algae, achieving simultaneous fertilization and purification; at the same time, they inhibit the reproduction of harmful bacteria (such as Vibrio), reducing the risk of aquaculture diseases. Zooplankton feed on phytoplankton, controlling algal density and preventing water hypoxia caused by excessive algal growth; they themselves are also high-quality natural food for fish and shrimp fry, improving fry survival rates and growth rates. This fertilization method is effective for the longsnout catfish, which exhibits strong stress responses and difficulty in starting feeding. It is important to note that the initial feed obtained using this method needs to be combined with finely ground artificial feed to ensure a relatively high survival rate for the fry.

[0093] In addition to the seedling stage, the fertilization method of this scheme can also be used in the adult fish cultivation stage of long-snout catfish, with the following advantages: (1) Construct an ecological barrier in the water body and balance the algal and bacterial communities. Feeding adult long-snout catfish with high-protein formulated feed can lead to the accumulation of organic matter in the water due to uneaten feed and feces, easily causing excessive levels of ammonia nitrogen and nitrite. Moderate fertilization can cultivate beneficial algae such as diatoms and green algae. These algae absorb nutrients such as nitrogen and phosphorus from the water through photosynthesis, reducing the concentration of harmful substances. At the same time, algae provide a habitat for beneficial bacteria (such as Bacillus), forming a virtuous cycle of "algae-bacteria-water" and maintaining water quality stability.

[0094] (2) Indirectly increases dissolved oxygen and alleviates hypoxia stress The photosynthesis of beneficial algae is an important source of dissolved oxygen in water bodies. Especially on sunny afternoons, the oxygen produced by algae can significantly increase the dissolved oxygen level in water bodies and alleviate the problem of insufficient dissolved oxygen under high-density aquaculture.

[0095] (3) Reduce stress response and improve physical condition in long-snout catfish Adult longsnout catfish prefer a clean and slightly fertile micro-flowing water environment. Completely nutrient-poor water (transparency > 50cm) will result in weak water buffering capacity, large diurnal pH fluctuations, and easy stress on the fish. Moderately fertile water can stabilize the pH value of the water (7.0-8.5) and reduce the probability of stress-related diseases (such as gill rot and skin ulcers).

[0096] (4) It helps save feed costs and improve growth efficiency. Zooplankton and organic detritus cultivated in fertile water can serve as supplementary feed for adult longsnout catfish, providing natural protein and trace elements and reducing the amount of artificial formulated feed required. Especially during the peak growth season for longsnout catfish (water temperature 20-28℃), supplementary feed can improve feed conversion rate and reduce farming costs.

[0097] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A high-efficiency large-scale artificial breeding method of Leiocassis longirostris, characterized by comprising the following steps: The process includes the following steps: placing long-snout catfish fry into a rearing pond for culture; the water in the rearing pond is fresh culture water that has been treated with fertilizer, and the water in the rearing pond contains the first food for the long-snout catfish fry; the first food includes rotifers and cladocerans; ​ The method for treating aquaculture water with fertilizer is as follows: after filling the seedling pond with fresh aquaculture water, sprinkle soybean milk, dispersion of bacterial and algal nutrient paste, and dispersion of algal polypeptide on the water surface. The amount of soybean milk used is 2.5-5 kg / mu·m per day, for 5 consecutive days; The dosage of the fungal and algal nutrient paste is 100-150 grams per mu·meter per day, and it should only be applied on the first day after applying the soybean milk. The dosage of algal polypeptide is 1.0-1.5 kg / mu·m per day, applied once every 5-7 days; Two to three days after the first application of soybean milk, algae nutrient paste dispersion, and algae-derived polypeptide dispersion to the water surface, apply 100-200 g / mu·m of rotifers to the water in the seedling pond. One to two days after the density of rotifers in the nursery reaches 10-20 individuals / mL and the density of cladocerans reaches 1-3 individuals / mL, the long-snout catfish fry are introduced into the nursery for cultivation.

2. The method according to claim 1, wherein the method is characterized by the following steps: During the rearing process of long-snout catfish fry, the water quality conditions in the rearing pond should be maintained as follows: dissolved oxygen ≥ 5 mg / L, pH 6.5-8.5, ammonia nitrogen ≤ 0.2 mg / L, nitrite ≤ 0.1 mg / L, sulfide ≤ 0.1 mg / L, and transparency 25-35 cm. The water in the seedling pond should be kept at a flow rate of 0.1-0.2 m / s, and 10-15% of the water in the seedling pond should be replaced with fresh aquaculture water every day.

3. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 2, characterized in that: One day before the long-snout catfish fry are released into the nursery pond for rearing, vitamin stress reliever is sprayed onto the surface of the nursery pond at a rate of 0.2-1 kg / mu·m. Soy milk is prepared by soaking soybeans for 10-12 hours at a volume ratio of water to soybeans of 2-3:1 to obtain soaked soybeans; when grinding, the soybeans are ground at a volume ratio of water to soaked soybeans of 2:1 to obtain soy milk.

4. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 1, characterized in that: The water quality conditions for the fresh aquaculture water injected into the seedling pond are: dissolved oxygen ≥ 5 mg / L, pH value 6.5-8.5, ammonia nitrogen ≤ 0.2 mg / L, nitrite ≤ 0.1 mg / L, sulfide ≤ 0.1 mg / L, transparency 25-35 cm, and the aquaculture water is filtered through a 60-80 mesh screen. Before filling the seedling pond with aquaculture water, use a high-pressure water gun to remove silt and debris from the bottom of the pond, and then disinfect it with 360-500g of chlorine dioxide per acre. The seedling pond is a cement pond with an area of ​​1.0-2.0 mu and a water depth of ≥1.8m.

5. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 1, characterized in that: The seedling pond is equipped with a feeding mechanism; The feeding mechanism includes a shaded canopy with its top and four sides covered by shading cloth. The canopy measures 1-2m in length, 1-1.5m in width, and 0.6-1.0m in height. A feeder with a light source is suspended in the center of the top of the canopy. The light intensity of the light source on the feeder is controlled at 200–400 μmol / m². 2 The distance between the light source and the water surface is controlled at 0.3-0.6m; The shade canopy is fixed to a micro-flow device at the bottom; the micro-flow device is fixed above the water surface by supporting legs; the distance between the top of the shade canopy and the water surface is ≤1.2m; the micro-flow device is used to drain water into the seedling pond to create a micro-flow environment; Fish fry hiding places are randomly placed in the water below the feeding facility.

6. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 1, characterized in that: In the seedling cultivation process, the artificial feed is fed to the long-snout catfish fry in the following way: During the larval stage of the long-snout catfish: Longsnout catfish fry were fed with powdered feed, which was sieved through a screen with a mesh size of ≥80. The feed amount accounted for 5-8% of the fry's body weight, and the protein content of the powdered feed was 46-48%. In the juvenile stage I of the long-snout catfish fry: For the first 3-5 days, the feed should be gradually changed from powdered feed to microparticle feed; the protein content of microparticle feed is 46-48%; On the first day of the first stage of juvenile fish, feed them 90%-95% powdered feed and 5%-10% microparticle feed. Then, gradually increase the proportion of pelleted feed every day until the third to fifth day when they are fed 100% microparticle feed. Then continue feeding with microparticle feed until the end of stage I fry; the microparticle feed is sieved through a ≥60 mesh screen; In the juvenile stage II of the long-snout catfish fry: For the first 3-5 days, the feed should be transitioned from microparticle feed to pellet feed; the protein content of the pellet feed should be 40-48%; the particle size of the pellet feed should be 1-2 mm. On the first day of the second stage of juvenile fish, feed them 90%-95% microparticle feed and 5%-10% pellet feed. Then, gradually increase the proportion of pellet feed each day until the third to fifth day when they are fed 100% pellet feed.

7. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 6, characterized in that: In the seedling cultivation process, the artificial feed is fed to the long-snout catfish fry in the following way: During the larval stage of the long-snout catfish: Four to five days after hatching, a continuous feeding pattern with the lights on all day was adopted. Six to seven days after hatching, the lights should be on all day and the food should be fed twice a day at set times. In the juvenile stage I of the long-snout catfish fry: The fish were kept lit all day and fed three times a day at set times. The total daily feed amount as a percentage of the fish fry's body weight was gradually increased from 5%-8% to 8%-12% each day. In the juvenile stage II of the long-snout catfish fry: The fish are kept lit all day and fed three times a day at set times; the total daily feed amount accounts for 10-15% of the fish fry's body weight.

8. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 7, characterized in that: During the larval stage of longsnout catfish, which is 4-7 days after hatching, the stocking density is 100,000-150,000 fish / acre. From 6-7 days after hatching, feeding should be done twice daily at fixed times: once in the morning from 8:00-9:00, accounting for 50-70% of the total daily feed; and once in the afternoon from 18:00-19:00, accounting for 30-50% of the total daily feed. Each feeding session should last 1.0-1.5 hours. During the juvenile stage I of long-snout catfish fry, which is 8-20 days after hatching, the stocking density is 50,000-80,000 fish / acre. During the second juvenile stage of long-snout catfish fry, which is 21-30 days after hatching, the stocking density is 20,000-30,000 fish / acre. For juvenile fish in stages I and II, feeding should be done three times a day at set times: once from 08:00 to 09:00 in the morning, accounting for 50-70% of the total daily feed; once from 18:00 to 19:00 in the afternoon, accounting for 15-25% of the total daily feed; and once from 19:00 to 20:00 in the evening, accounting for 15-25% of the total daily feed. Each feeding session should last for 1.0-1.5 hours.

9. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 1, characterized in that: Longsnout catfish fry are obtained as follows: Longsnout catfish sperm cells and egg cells are mixed to form fertilized eggs, which are then poured into a hatching pond. The fertilized eggs are scooped up from the hatching pond using a net, allowing them to attach to the net. The net is then suspended in the hatching pond, ensuring all fertilized eggs are below the water surface. The water is maintained at dissolved oxygen 6-8 mg / L, water transparency 25-30 cm, pH 7.0-8.5, ammonia nitrogen <0.02 mg / L, and nitrite <0.01 mg / L. After the fry hatch, they are temporarily raised in the hatching pond for 1-2 days before being transferred to a nursery pond.

10. The efficient and large-scale artificial breeding method for *Catfish simonii* according to claim 9, characterized in that: The hatching pond is prepared by the following method: soaking the drained hatching pond with oxalic acid solution, and then disinfecting with chlorine dioxide; then injecting clean water, and maintaining the water level at 1.2-1.5 m, the temperature at 24-26℃, the dissolved oxygen at ≥5 mg / L, and the pH at 7.0-8.5; the area of the hatching pond is 3-5 m 2 ; A rope is hung horizontally above the hatching pool to suspend the netting.

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