Leiocassis longirostris shed-pond relay breeding method

Abstract

The invention discloses a leiocassis longirostris shed-pond relay culture method. The method comprises the following three steps: (1) fine culture in a greenhouse circulating water system; (2) shed-pond relay transfer; and (3) extensive culture in a large-water-surface pond. According to the method, water quality regulation and control, accurate feeding and water resource saving are achieved through circulating water culture, large-scale rapid weight increment of the leiocassis longirostris is achieved through pond culture, the bottleneck of a traditional culture mode is broken through, and the culture mode with stable water quality, controllable diseases and efficient utilization of resources is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aquaculture, and particularly relates to a relay culture method for Leiocassis longirostris in shed ponds. Background Art

[0002] Leiocassis longirostris has a smooth and scaleless body surface. Its body is elongated and spindle-shaped, thick and short in the front part and laterally compressed in the rear part. The back of the body is grayish-black, the abdomen is light-colored or white, and irregular purplish-gray patches are scattered on the body side. It is commonly known as "Jiangtuan" and belongs to eurythermal carnivorous fish. It likes to gather and is light-averse. It is widely distributed in the main streams and tributaries of the Yangtze River in China and its affiliated lakes, and is one of the precious economic fish species unique to China. Its meat is tender without intermuscular spines, rich in protein and unsaturated fatty acids, and has high edible and market value. The survival temperature is 0 - 38°C, and the suitable growth temperature is 24 - 28°C. When the water temperature is lower than 15°C, it stops feeding. The survival pH range is 6.5 - 9.0, and the optimal pH is 7.0 - 8.4. The total alkalinity is maintained at about 150mg / L CaCO3. This fish has poor oxygen tolerance, and the dissolved oxygen (DO) should be maintained > 5mg / L during farming. When the dissolved oxygen is as low as 2.5mg / L, it is easy to float on the water surface. In the natural environment, it mostly inhabits slow-flowing waters with sandy or rocky bottoms and feeds on small fish, crustaceans, and benthic invertebrates. Due to overfishing and habitat destruction, its wild resources have sharply decreased, and artificial farming has become the main way to ensure market supply.

[0003] At present, the large-scale farming of Leiocassis longirostris mainly relies on two traditional modes: pond farming and cage farming. The traditional farming modes have problems such as difficult water quality regulation, low precision of feed feeding, and waste of water resources. The water quality management of the traditional farming mode lacks real-time monitoring and dynamic regulation, which easily leads to problems such as the accumulation of ammonia nitrogen and nitrite, unstable dissolved oxygen, and pH fluctuations, resulting in fish diseases or deaths. The traditional feeding mode is extensive and lacks dynamic adaptation to feeding behavior, causing resource waste and growth inhibition. The traditional farming mode relies on large amounts of water replacement, with low water resource utilization rate, and the direct discharge of eutrophicated tail water is likely to cause pollution to the surrounding water bodies, going against the development trend of green farming. Therefore, how to improve the drawbacks of the traditional farming mode of Leiocassis longirostris is an urgent problem we need to solve currently. Summary of the Invention

[0004] The present invention aims to provide a relay culture method for Leiocassis longirostris, that is, a relay culture mode of land-based industrialized recirculating water and ponds for Leiocassis longirostris. Through recirculating water culture, water quality regulation, precise feeding, and water resource conservation are achieved. Through pond culture, large-scale and rapid weight gain of Leiocassis longirostris is realized, breaking through the bottleneck of the traditional farming mode, and achieving a farming mode with stable water quality, controllable diseases, and efficient resource utilization.

[0005] The present invention is realized through the following technical solutions:

[0006] A method for relay farming of Leiocassis longirostris in greenhouse ponds, specifically including the following steps:

[0007] (1) Fine farming in the greenhouse circulating water system

[0008] In October of the first year, use the inland-based industrialized circulating water system in the greenhouse to farm Leiocassis longirostris seedlings, including the construction of the circulating water farming system, the preparation of tools and consumables, the preparation of feed, animal protection products, and fishery drugs, the preparation of farming water, the stocking of seedlings, and farming management;

[0009] (2) Relay transfer in greenhouse ponds

[0010] In May of the second year, when Leiocassis longirostris grows to more than 70g, transfer the Leiocassis longirostris that meets the specifications and is in good condition to the large water surface pond for farming. The transfer process includes the steps of transfer preparation, screening of transferred Leiocassis longirostris, transfer facilities and methods, environmental adaptation, and live preservation measures;

[0011] (3) Extensive farming in large water surface ponds

[0012] Use the large water surface pond for the subsequent farming and growth process of Leiocassis longirostris, including pond preparation, water quality requirements, feeding, and farming management.

[0013] Preferably, the construction of the circulating water farming system in step (1) means that the farming system should have the conventional equipment of the circulating water farming system, at least including farming containers, solid-liquid separators, fluidized beds, temperature control equipment, aeration facilities, pure oxygen tanks, standby water sources, and power sources. After cleaning and disinfecting the farming environment, it should be checked whether the system can operate normally. Among them, the normal operation of the solid-liquid separator includes three steps: ① Clean the solid-liquid separator. ② The water level sensor can operate normally. When the water level rises to the sensor closure, start backwashing. ③ Clean the backwashing nozzle. Among them, before releasing the seedlings, the fluidized bed should be "coated with film" and mature, with a nitrogen treatment load capable of handling the corresponding farming capacity. The inspection content of this item includes: ① The aeration facilities in the fluidized bed can make the filter media evenly suspended. ② The filter media in the fluidized bed should be coated with film and mature. The film coating operation is: add crushed feed of 100mg / L of the fluidized bed water volume in the fluidized bed, add sodium bicarbonate (NaHCO3) to maintain the total alkalinity at about 150mg / L CaCO3 until the total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) are close to 0mg / L. ③ After film coating, the farming system can handle 5mg / L of ammonia nitrogen in the farming water (corresponding amounts of ammonium chloride or ammonium sulfate can be added), and the ammonia nitrogen is reduced to below 0.5mg / L within 5 hours, and no obvious increase in nitrite is seen. Among them, the standby water source should ensure a water source of 1 / 3 of the farming volume, and when the fish needs to be medicated, etc., water can be changed. The standby power source should be equipped with a generator (or pure oxygen) to prevent power outages, etc. Among them, the normal operation of the system means that after the system is filled with water, the power of the heating equipment can reach the requirements, and the aeration facilities and circulation pumps can operate normally.

[0014] Preferably, for the preparation of tools and consumables in step (1), the tools include various types of dip nets, small buckets, turnover boxes, large buckets, scales, dippers, feeding platforms, aeration supplies, sunshade facilities, and other common tools; the consumables include total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, hydrogen sulfide, total alkalinity, residual chlorine test kits, etc., and water conditioning supplies such as baking soda and sodium thiosulfate.

[0015] Preferably, for the preparation of feed, animal health products, and fishery drugs in step (1), the feed includes compound feeds with different particle sizes, and the compound feed specialized for Leiocassis longirostris is the best (the crude protein is between 40% and 45%). Animal health products include: Bacillus subtilis and EM bacteria, multivitamins, astragalus polysaccharide, liver and gall protection products, lactic acid bacteria, etc. Fishery drugs include: enrofloxacin, florfenicol, povidone iodine, trichlorfon, potassium permanganate, etc.

[0016] Preferably, the preparation of aquaculture water in step (1) refers to paying attention to water temperature and residual chlorine problems. Leiocassis longirostris is a eurythermal fish, and the transportation water temperature and the water temperature for releasing fry should be considered, and the difference should not be too large. Leiocassis longirostris is a scaleless fish and is very sensitive to residual chlorine. When using tap water for aquaculture, the water should be filled at least 3 days in advance and aerated to remove residual chlorine. One day before releasing fry, it should be ensured that the residual chlorine < 0.02 ppm. If the residual chlorine exceeds the standard, sodium thiosulfate can be used to remove it. This fish is particularly sensitive to residual chlorine, and it should also be noted that when the system is operating, the addition of new tap water may cause an increase in residual chlorine.

[0017] Preferably, for the release of fry in step (1), different fry release preparations should be adopted according to the transportation method of the fry. When the fry are transported by water truck, unload the fry into a large bucket or turnover box and disinfect them with povidone iodine. At the same time, gradually adjust the water temperature in the bucket or turnover box to be less than 1°C different from the water temperature in the culture tank, and note that during this process, the fry are likely to be oxygen-deficient, and aeration equipment or even pure oxygen must be added to ensure that DO > 2.5 mg / L; when the fry are transported in oxygen-filled packaging bags, after the fry arrive, put the bags into the culture tank and soak for 15 - 30 min, then pour the fry into a large bucket or turnover box and disinfect them with povidone iodine. Similarly, pay attention to the dissolved oxygen problem. While disinfecting the fry, sprinkle multivitamins in all the culture tanks to avoid stress on the fry. After disinfection, scoop the fish into the culture tank with a dip net.

[0018] Preferably, feeding should start 24 hours after the fry enter the system. Due to the long transportation time of the fry, the daily feeding amount at the beginning is preferably 4 - 6‰. The first feeding time is at dusk (5 - 7 o'clock), and 2 hours later, lift the feeding platform and check the feeding situation by scraping the bottom. Pay attention to distinguishing between residual bait and feces. If there is a lot of residual bait and little feces, feeding should be stopped and resumed the next day with the feeding amount halved. Repeat this process until no residual bait is seen after the fry have eaten. At this time, the feeding amount is increased by 10% every 2 - 3 days until the feeding amount reaches 4 - 6%.

[0019] Preferably, after long-distance transportation, fry are inevitably mechanically damaged. To prevent the wounds from being infected by Saprolegnia, 24 hours after the fry enter the culture tank, the water temperature can be increased by 2°C every day to prevent Saprolegnia. In the morning after the first feeding, TAN, NO2-N, and NO3-N should be detected. If it is found that TAN or NO2-N accumulates (TAN > 0.3 mg / L, NO2-N > 0.15 mg / L), feeding should be stopped, and at this time, Bacillus spp. (5 ppm) and glucose (10 ppm) should be evenly sprayed throughout the pond.

[0020] Preferably, if it is found that the fish swim rapidly along the pool wall and jump, consider whether the light is too strong. If this situation still occurs after excluding the light, then consider whether there are other problems such as parasites.

[0021] Preferably, during the breeding process, TAN < 0.3 mg / L and NO2-N < 0.15 mg / L should be maintained, and the remaining indicators should be adjusted according to the biological characteristics of Leiocassis longirostris. For the regulation and management of water quality, pay attention to the principle of "small amounts and multiple times".

[0022] Preferably, the daily feeding amount should be 4-6% of the body weight. At 10:00 am, 30-40% of the daily feeding amount is fed, and at 5:00 pm, 60-70% is fed. During daily feeding, animal health products such as astragalus polysaccharide, lactic acid bacteria, and multi-vitamins should be mixed according to the growth of the fry. Note that the mixing should be completed within 30 minutes before feeding. Generally, the total mass of the mixed materials and water is 10% of the feed quality, and feeding is quantitatively carried out according to the demand. After feeding, pay attention to daily bottom scraping and checking the feeding platform to judge the feeding situation.

[0023] Preferably, Leiocassis longirostris has no scales and is prone to body ulceration, enteritis, gill rot, bleeding and other conditions during the breeding process. In daily management, strengthen inspections and detect and treat them as early as possible. There are many devices in the recirculating aquaculture system. During daily inspections, attention should be paid to the operation of devices and facilities such as water pumps, water valves, inlets, and outlets. If ulcer disease occurs, the following treatment plan can be adopted: Taking 10 cubic meters of water body, 2500 fish (20 g / fish), and a feeding amount of 150 g / day as an example: ① Mix 5 ml of Xinbaiankang and 10 ml of Wuhuangjintai and spray them evenly. After 2 hours, add 10 g of Anjing, change the water after 12 hours, once a day, and spray continuously for 2-3 days. ② Dissolve 3 g of Anjing, 2 g of Gandankang, and 2 g of astragalus in water and then mix with the feed, twice a day, and feed continuously for 6-7 days. ③ After recovery, regularly mix Gandankang and astragalus with the feed, feed for 5 days, stop for 7-10 days, and cycle.

[0024] Preferably, the transfer preparation in step (2) refers to fasting before pond stocking and feeding vitamin C; the screening of the transferred Leiocassis longirostris refers to screening out Leiocassis longirostris that reach a certain specification for transfer; the transfer facilities and methods refer to loading the Leiocassis longirostris that meet the pond stocking specification into a sorting box and transporting them using a water truck; the environmental adaptation and live preservation refer to the water in the sorting box being the original aquaculture water body. First, disinfect it with drugs such as povidone iodine and sodium chloride, and then soak the Leiocassis longirostris bag in the water for about 30 minutes to make it adapt to the water temperature before pond stocking. Do not feed after pond stocking.

[0025] Preferably, the pond preparation in step (3) refers to pond construction, disinfection, and cleaning; the water quality requirements refer to the aquaculture water body reaching the best state, including a water temperature of 24 - 28 °C, a pH value of 7.0 - 8.4, a dissolved oxygen > 5 mg / L, and a total alkalinity maintained at about 150 mg / L CaCO3; the feeding and aquaculture management refer to fasting for 2 - 3 days after pond stocking. After adaptation, feed the special feed for Leiocassis longirostris and implement the principles of "fixed quality, fixed quantity, fixed time, and fixed location". Subsequent aquaculture management includes daily inspections, health assessments, and water change regulation.

[0026] Beneficial effects: The present invention relates to a relay pond - shed culture method for Leiocassis longirostris, aiming to achieve water quality regulation, precise feeding, and water resource conservation through recirculating aquaculture, and to achieve large - scale and rapid weight gain of Leiocassis longirostris through pond culture, break through the bottleneck of the traditional culture mode, and achieve stable water quality, controllable diseases, and efficient utilization of resources. Specific embodiments

[0027] The following details the embodiments of the present invention: These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0028] Embodiment:

[0029] A relay pond - shed culture method for Leiocassis longirostris specifically includes the following steps:

[0030] Step 1: Fine farming in the greenhouse recirculating water system. Build a recirculating water aquaculture system, including aquaculture containers, solid-liquid separators, fluidized beds, temperature control equipment, aeration facilities, pure oxygen tanks, standby water sources, and power sources. Check that the solid-liquid separator can operate normally. Add crushed feed at a dosage of 100 mg / L of the fluidized bed water volume to the fluidized bed, and add sodium bicarbonate (NaHCO3) to maintain the total alkalinity at about 150 mg / L CaCO3 until the total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) are close to 0 mg / L. After the "biofilm formation" in the fluidized bed is mature, the aquaculture system can handle 5 mg / L of ammonia nitrogen in the aquaculture water (ammonium chloride or ammonium sulfate can be added in corresponding amounts), and the ammonia nitrogen is reduced to less than 0.5 mg / L within 5 hours, with no obvious increase in nitrite. The standby water source should ensure a water source of 1 / 3 of the aquaculture volume, and the standby power source should be equipped with a generator (or pure oxygen) in case of power outage. After cleaning and disinfecting the aquaculture environment, check whether the system can operate normally, that is, after the system is filled with water, the power of the heating equipment can meet the requirements, and the aeration facilities and circulation pumps can operate normally. Prepare tools and consumables. Tools include various types of dip nets, small buckets, turnover boxes, large buckets, scales, dippers, feeding platforms, aeration supplies, sunshade facilities, and other commonly used tools. Consumables include total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, hydrogen sulfide, total alkalinity, residual chlorine test kits, etc., and water conditioning supplies such as baking soda and sodium thiosulfate. Prepare feed, animal health products, and fishery drugs. The feed includes compound feeds with different particle sizes, and the compound feed specific to Leiocassis longirostris is the best (crude protein ranges from 40% to 45%). Animal health products include: Bacillus subtilis and EM bacteria, multi-vitamins, astragalus polysaccharides, liver and gall protection products, lactic acid bacteria, etc. Fishery drugs include: enrofloxacin, florfenicol, povidone iodine, trichlorfon, potassium permanganate, etc.

[0031] Select healthy and vigorous catfish fry in October every year, about 12 fry per kilogram, with a total of 6,000 fry released, weighing 125 kilograms. The area of the breeding barrels in the shed is 30 square meters. Fill the water 3 days in advance and aerate to remove residual chlorine. One day before releasing the fry, ensure that the residual chlorine < 0.02 ppm. Disinfect with povidone iodine when releasing the fry, gradually adjust the water temperature in the barrel or turnover box to be less than 1°C different from the water temperature in the breeding tank, and at the same time add an aeration device or even supply pure oxygen to ensure that DO > 2.5 mg / L. While disinfecting the fry, sprinkle multivitamins in all breeding tanks to avoid stress in the fry. At 5 - 7 pm, 24 hours later, start the first feeding, with a daily feeding amount of 4 - 6‰. Check the feeding situation by lifting the feeding platform and scraping the bottom 2 hours later. Pay attention to distinguish between residual bait and feces. If there is a lot of residual bait and little feces, stop feeding and resume feeding the next day with half the feeding amount. Repeat this process until there is no residual bait after the fry have eaten. At this time, increase the feeding amount by 10% every 2 - 3 days until the feeding amount reaches 4 - 6%. At the same time, to prevent water mold, the water temperature can be raised by 2°C every day for prevention 24 hours after the fry enter the breeding tank. In the morning after the first feeding, TAN, NO2-N, and NO3-N should be detected. If there is an accumulation of TAN or NO2-N (TAN > 0.3 mg / L, NO2-N > 0.15 mg / L), stop feeding and at this time, sprinkle Bacillus sp. (5 ppm) and glucose (10 ppm) throughout the pond. If it is found that the fish swim rapidly along the pool wall and jump, consider whether the light is too strong. If this situation still occurs after excluding the light, consider other problems such as parasites.

[0032] Step 2: Conduct relay transfer between the shed and the pond in May of the second year. When the catfish grow to more than 70 g, transfer the catfish that meet the specifications and are in good condition to a large water surface pond for breeding. Fast before transfer and feed vitamin C. Load the catfish that meet the pond entry specifications into the sorting box and transport them using a water truck. The water in the sorting box is the original breeding water body. First, disinfect with drugs such as povidone iodine and sodium chloride, and then soak the catfish bag in water for about 30 minutes to make it adapt to the water temperature before putting it into the pond. Do not feed after putting it into the pond.

[0033] Step 3: Use the large water surface pond for the subsequent breeding and growth of catfish. The water temperature of the pond breeding water body is 24 - 28°C, pH value is 7.0 - 8.4, dissolved oxygen > 5 mg / L, and the total alkalinity is maintained at about 150 mg / L CaCO3. The stocking weight per mu of the pond is 126 kilograms, and 1,600 fish are stocked per mu. Stop feeding for 2 - 3 days after putting it into the pond. After adaptation, feed the special feed for catfish and implement the principles of "fixed quality, fixed quantity, fixed time, and fixed position". Subsequent breeding management includes daily inspections, health assessments, and water change regulation.

[0034] Through this aquaculture mode, the survival rate after recirculating aquaculture can reach 97.4%. After pond large-water-surface aquaculture, the out-of-pond scale can reach 1.5 kg per tail, the survival rate is about 76%, and the yield per mu of cultured fish is about 1824 kg. This relay aquaculture mode between greenhouse and pond can break through the bottleneck of the traditional aquaculture mode, realize water quality regulation, precise feeding and water resource conservation, enable large-scale and rapid weight gain of Leiocassis longirostris, save costs and efficiently utilize resources.

[0035] The above content is only an example and illustration of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only explains the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A relay culture method for Leiocassis longirostris in ponds, characterized in that, Specifically, it includes the following steps: (1) Fine farming in the greenhouse recirculating water system In October of the first year, use the inland-based industrialized recirculating water system in the greenhouse to breed the fry of Leiocassis longirostris, including the construction of the recirculating water aquaculture system, the preparation of tools and consumables, the preparation of feed, animal health products, and fishery drugs, the preparation of aquaculture water, the stocking of fry, and aquaculture management; (2) Relay transfer between greenhouse and pond In May of the second year, when the Leiocassis longirostris grows to more than 70g, transfer the Leiocassis longirostris that meets the specifications and is in good condition to the large water surface pond for aquaculture. The transfer process includes steps such as transfer preparation, screening of transferred Leiocassis longirostris, transfer facilities and methods, environmental adaptation, and live preservation measures; (3) Extensive farming in the large water surface pond Use the large water surface pond for the subsequent aquaculture growth process of Leiocassis longirostris, including pond preparation, water quality requirements, feeding, and aquaculture management.

2. The method for relay farming of Leiocassis longirostris in ponds according to claim 1, wherein The construction of the recirculating water aquaculture system in step (1) means that the aquaculture system should be equipped with conventional equipment for the recirculating water aquaculture system, including at least aquaculture containers, solid-liquid separators, fluidized beds, temperature control equipment, aeration facilities, pure oxygen tanks, standby water sources, and power sources. After cleaning and disinfecting the aquaculture environment, it should be checked whether the system can operate normally. Among them, the normal operation of the solid-liquid separator includes three steps: ① Clean the solid-liquid separator. ② The water level sensor can operate normally. When the water level rises to the point where the sensor closes, start backwashing. ③ Clean the backwashing nozzle. Among them, before stocking the fry, the fluidized bed should be "biofilm-coated" and mature, with a nitrogen treatment load capable of handling the corresponding aquaculture capacity. The inspection content includes: ① The aeration facilities in the fluidized bed can evenly suspend the filter media. ② The filter media in the fluidized bed should be biofilm-coated and mature. The biofilm-coating operation is as follows: Add pulverized feed at 100mg / L of the fluidized bed water volume to the fluidized bed, and add sodium bicarbonate (NaHCO3) to maintain the total alkalinity at about 150mg / L CaCO3 until the total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) are close to 0mg / L. ③ After biofilm-coating, the aquaculture system can handle 5mg / L of ammonia nitrogen in the aquaculture water (ammonium chloride or ammonium sulfate can be added in the corresponding amount), and the ammonia nitrogen is reduced to below 0.5mg / L within 5 hours, and no obvious increase in nitrite is seen. Among them, the standby water source should ensure a water source of 1 / 3 of the aquaculture volume, and when the fish needs to be medicated, etc., water can be changed. The standby power source should be equipped with a generator (or pure oxygen) to prevent power outages and other situations. Among them, the normal operation of the system means that after the system is filled with water, the power of the heating equipment can reach the requirements, and the aeration facilities and the circulation pump can operate normally.

3. A method for relay farming of Leiocassis longirostris in ponds according to claim 1, characterized in that, For the preparation of tools and consumables in step (1), the tools include various types of dip nets, small buckets, turnover boxes, large buckets, scales, ladles, feeding platforms, aeration supplies, sunshade facilities, and other commonly used tools, etc.; the consumables include total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, hydrogen sulfide, total alkalinity, residual chlorine test kits, etc. and water quality conditioning supplies such as baking soda and sodium thiosulfate.

4. A method for relay culture of Leiocassis longirostris in ponds according to claim 1, characterized in that, The preparation of feed, animal health products, and fishery drugs in step (1), where the feed includes compound feeds with different particle sizes, and the compound feed specific to Leiocassis longirostris is preferred (with crude protein ranging from 40% to 45%). Animal health products include: Bacillus subtilis and EM bacteria, multi-vitamins, astragalus polysaccharide, liver and gallbladder protection products, lactic acid bacteria, etc. Fishery drugs include: enrofloxacin, florfenicol, povidone iodine, trichlorfon, potassium permanganate, etc.

5. A method for relay culture of Leiocassis longirostris in ponds according to claim 1, characterized in that, The preparation of aquaculture water in step (1) refers to paying attention to water temperature and residual chlorine problems. Leiocassis longirostris is a eurythermal fish, and the transportation water temperature and the water temperature for releasing fry should be considered, and the difference should not be too large. Leiocassis longirostris is a scaleless fish and is very sensitive to residual chlorine. When using tap water for aquaculture, the water should be filled at least 3 days in advance and aerated to remove residual chlorine. One day before releasing fry, it should be ensured that the residual chlorine < 0.02 ppm. If the residual chlorine exceeds the standard, sodium thiosulfate can be used to remove it. This fish is especially sensitive to residual chlorine, and it should also be noted that when the system is running, the addition of new tap water may cause the residual chlorine to increase.

6. A method for relay culture of Leiocassis longirostris in ponds, according to claim 1, characterized in that The fry stocking in step (1) means that different fry stocking preparations should be adopted according to the transportation method of the fry. When the fry are transported by water truck, unload the fry into a large bucket or turnover box and disinfect them with povidone iodine. At the same time, gradually adjust the water temperature in the bucket or turnover box to be less than 1°C different from the water temperature in the culture tank. Note that during this process, the fry are likely to be short of oxygen, and aeration equipment or even pure oxygen must be added to ensure DO > 2.5 mg / L; when the fry are transported in oxygen-filled packaging bags, after the fry arrive, put the bags into the culture tank and soak for 15 - 30 minutes, then pour the fry into a large bucket or turnover box and disinfect them with povidone iodine. Similarly, pay attention to the dissolved oxygen problem. While disinfecting the fry, sprinkle multi-vitamins on all the culture tanks to avoid fry stress. After disinfection, scoop the fish into the culture tank with a scoop net.

7. A method for relay culture of Leiocassis longirostris in ponds, according to claim 1, characterized in that, Feeding should start 24 hours after the fry enter the system. Due to the long transportation time of the fry, the daily feeding amount at the beginning is preferably 4 - 6‰. The first feeding time is at dusk (5 - 7 o'clock in the evening). Check the feeding situation by lifting the feeding platform and scraping the bottom 2 hours later. Pay attention to distinguishing between residual bait and feces. If there is a lot of residual bait and little feces, feeding should be stopped and resumed the next day with the feeding amount halved. Repeat this process until there is no residual bait after the fry feed. At this time, the feeding amount is increased by 10% every 2 - 3 days until the feeding amount reaches 4 - 6%.

8. A method for relay culture of Leiocassis longirostris in ponds, according to claim 1, characterized in that, After long-distance transportation, the fry will inevitably have mechanical injuries. To avoid wound infection by Saprolegnia, 24 hours after the fry enter the culture tank, the water temperature can be raised by 2°C every day to prevent water mold. In the morning after the first feeding, TAN, NO2-N, and NO3-N should be detected. If it is found that TAN or NO2-N accumulates (TAN > 0.3 mg / L, NO2-N > 0.15 mg / L), feeding should be stopped, and at this time, Bacillus bacteria (5 ppm) and glucose (10 ppm) should be sprayed all over the pond.

9. A method for relay farming of Leiocassis longirostris in a pond, characterized in that, If it is found that the fish swim rapidly along the pool wall and jump, consider whether the light is too strong. If this situation still occurs after excluding the light, then consider whether there are other problems such as parasites.

10. The method for relay farming of Leiocassis longirostris in ponds according to claim 1, characterized in that, During the breeding process, TAN should be maintained at < 0.3 mg / L, NO2-N at < 0.15 mg / L, and the remaining indicators should be adjusted according to the biological characteristics of Leiocassis longirostris. For the regulation and management of water quality, pay attention to the principle of "small amount and multiple times".

11. The method for relay farming of Leiocassis longirostris in ponds according to claim 1 is characterized in that, The daily feeding amount should be 4-6% of the body weight. Feed 30-40% of the daily feeding amount at 10:00 am and 60-70% at 5:00 pm. During daily feeding, animal health products such as astragalus polysaccharide, lactic acid bacteria, and multi-vitamins should be mixed according to the growth of fry. Note that the mixing should be completed within 30 minutes before feeding. Generally, the total mass of the mixed materials and water is 10% of the feed mass, and feed according to the demand. After feeding, pay attention to daily bottom scraping and checking the feeding table to judge the feeding situation.

12. A method for relay farming of Leiocassis longirostris in ponds, according to claim 1, characterized in that, Leiocassis longirostris has no scales and is prone to diseases such as body ulceration, enteritis, gill rot, and bleeding during the breeding process. Strengthen inspections during daily management and detect and treat early. There are many equipment in the recirculating aquaculture system. During daily inspections, pay attention to the operation of equipment and facilities such as water pumps, water valves, inlets, and outlets. If ulcer disease occurs, the following treatment plan can be adopted: Taking 10 cubic meters of water body, 2,500 fish (20 g / fish), and a feeding amount of 150 g / day as an example: ① Mix 5 ml of Xinbaiankang and 10 ml of Wuhuangjintai and sprinkle them evenly. Add 10 g of Anjing 2 hours later, change the water 12 hours later, once a day, and sprinkle continuously for 2-3 days. ② Dissolve 3 g of Anjing, 2 g of Gandankang, and 2 g of astragalus in water and mix with the feed, twice a day, and feed continuously for 6-7 days. ③ After recovery, regularly mix Gandankang and astragalus with the feed, feed for 5 days, stop for 7-10 days, and cycle.

13. The method for relay farming of Leiocassis longirostris in pond according to claim 1, characterized in that, The transfer preparation in step (2) refers to fasting before pond stocking and feeding vitamin C; the screening of transferred Leiocassis longirostris refers to screening Leiocassis longirostris that reach a certain specification for transfer; the transfer facilities and methods refer to loading Leiocassis longirostris that meet the pond stocking specification into a sorting box and transporting them using a water truck; the environment adaptation and live preservation refer to the water in the sorting box being the original breeding water body. First, disinfect it with drugs such as povidone iodine and sodium chloride, and then soak the Leiocassis longirostris bag in water for about 30 minutes to make it adapt to the water temperature before pond stocking. Do not feed after pond stocking.

14. A method for relay culture of Leiocassis longirostris in pond, as claimed in claim 1, wherein The pond preparation in step (3) refers to pond construction, disinfection, and cleaning; the water quality requirements refer to the best aquaculture water body, including a water temperature of 24-28 °C, a pH value of 7.0-8.4, a dissolved oxygen > 5 mg / L, and a total alkalinity maintained at about 150 mg / L CaCO3; the feeding and aquaculture management refer to stopping feeding for 2-3 days after pond stocking. After adaptation, feed the special feed for Leiocassis longirostris and implement the principles of "fixed quality, fixed quantity, fixed time, and fixed position". Subsequent aquaculture management includes daily inspections, health assessments, and water change regulation.