Large-scale breeding method of epinephelus based on outdoor-indoor relay cultivation

Abstract

This invention relates to the field of aquaculture technology, and more particularly to a method for large-scale grouper fry rearing based on outdoor-indoor relay rearing. The method includes: using black film ponds as outdoor hatching ponds, disinfecting and conditioning the water before controlling its quality; feeding grouper fertilized eggs in stages after hatching, adjusting the feed according to the mouth size of the fry, and preparing for transfer when 60% of the fry have a mouth size >2200μm; using PVC ponds as indoor rearing ponds, introducing water after multi-stage filtration, disinfection, and detoxification, and controlling the temperature to maintain an indoor-outdoor temperature difference of <2℃; transferring qualified fry to the indoor ponds, disinfecting them with a micro-flow of water, and then distributing them into the rearing ponds; cultivating, strengthening, and disinfecting live feed; feeding the fry in stages indoors according to mouth size, initiating feed acclimatization when 60% of the fry have a mouth size >5mm; controlling the fry density and conducting daily management. The advantages are: integrating the low-cost, large-scale outdoor operation with the high controllability of indoor rearing, improving fry survival rate and seedling quality, and meeting the needs of large-scale aquaculture.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, and in particular to a method for large-scale grouper breeding based on outdoor-indoor relay cultivation. Background Technology

[0002] Grouper is a highly valuable marine fish belonging to the family Serranidae, subfamily Epinephelinae, order Perciformes. Widely distributed in tropical and subtropical seas worldwide, they are important food and aquaculture fish. As a globally important economic fish, grouper possesses significant advantages in terms of consumption, aquaculture, and ecology, making them highly favored by fish farmers. They are extensively farmed in Hainan, Guangdong, and Fujian provinces of my country, becoming a crucial aquaculture species driving the development of coastal fisheries. Currently, grouper fry cultivation mainly employs two methods: outdoor pond hatching and indoor workshop hatching. However, both methods have certain technical shortcomings, making it difficult to balance fry yield, quality, and cultivation costs, severely restricting the large-scale, high-quality development of the grouper aquaculture industry.

[0003] Outdoor pond hatching and breeding (such as pond or offshore cage hatching) has advantages over indoor workshop hatching and breeding, such as lower cost and simpler operation. However, it also has problems such as strong environmental dependence and high risk of disease. Furthermore, in the later stages of hatching, the entire pond of fry is prone to sudden mortality, resulting in the waste of all previous efforts. Specifically, the typical technical process for outdoor pond hatching and breeding includes: 1. Hardware and water quality: A black film pond with an area of ​​2 acres is used, with a maximum water level of 2.6 meters. The pond walls are intact, the bottom slopes towards the center, the center is leak-proof, and water inlet and outlet are convenient. 2. Animal feed culture: A 3-acre pond is used, utilizing chicken manure fermentation for the targeted large-scale culture of single dominant species of animal feed organisms such as rotifers and copepods to ensure the fry's feed needs are met. 3. Pre-harvest water treatment: The pond must first be cleaned with a high-pressure water gun, then exposed to sunlight and disinfected with quicklime. After disinfection, it should be rinsed with water 2-3 times. The incoming water is filtered through a 150-mesh silk screen. The water source passes through a sand filter and sedimentation tank. After water intake, the water is disinfected, and the aerator is turned on for full aeration. Then, detoxification, algae addition, and water color enhancement and stabilization are performed. 4. Fertilized egg hatching and management: A hatching device is constructed on the pond surface. The hatching device uses a 110mm diameter PVC pipe frame, embedding tarpaulin hatching bags and securing the four corners. A shade net is erected above the hatching frame to avoid direct sunlight. After the fish egg bags arrive, they are first treated with 5g / m³ potassium permanganate. 3After disinfecting the surface of the bag and rinsing it clean, soak it in the incubation water for 15 minutes, then slowly place the fertilized eggs into the incubation bag. Adjust the aeration to just enough to lift the fertilized eggs. Check the hatching progress with a beaker every 2-3 hours. After the fry hatch, fill each of the four corners of the incubation bag with water, count the fry, and estimate the total number. 5. Water quality management: Do not add water for the first 1-12 days after opening the bag. After 12 days, begin slowly adding new water. The water quality will become clear in the later stages of fry rearing, making it prone to algae growth, which will affect the survival rate of the fry. Stabilize the water by continuously adding water containing Chlorella every day. 6. Fry rearing: On the morning of the fourth day after fertilization, the fry have developed mouths and eye spots, and can swim freely and feed. At this time, open the incubation bag and let the fry naturally enter the pond. One hour before opening the bag, sprinkle 500g of Vitamin C per acre to alleviate stress on the fry. From day 1 to 13 after opening the bag, collect rotifers and small copepods (larvae) from the rotifer-culture pond using a water pump and a 200-mesh silk screen for filtration. Feed them 6-8 times a day, maintaining a rotifer density of 3-10 rotifers / mL in the pond. From day 14 to 23, feed mainly copepods, gradually increasing their feeding amount while reducing the rotifer feeding amount. After day 24, supplement with fresh copepods, cladocerans, brine shrimp, and microencapsulated feed until the wings are fully recovered, at which point the pond can be netted and the rotifers removed. The problems with this model are: 1. Uncontrollable environmental and disease risks: Outdoor ponds rely on the natural environment. Especially after the newly hatched fry are 20 days old, the fry need a lot of nutrition during the fin-shrinking stage. However, the density of live feed in the pond decreases rapidly with feeding, so it is necessary to supplement with external feed. However, external feed (such as feed cultivated by fermenting chicken manure) carries a large number of harmful bacteria, and feeding in large quantities will increase the burden on the water body. Coupled with the inability to exchange water in large proportions in outdoor ponds, ammonia nitrogen and nitrite exceed the standards, the water quality deteriorates rapidly, and diseases are very likely to break out and cause "pond annihilation". At the same time, extreme weather (such as rainstorms) will cause drastic changes in dissolved oxygen, pH value, temperature and algae in the water, causing strong stress to the fry and further increasing the probability of pond annihilation. 2. Low fry quality and domestication efficiency: Even if some ponds survive the hatching period, the long-term deterioration of water quality still results in fry carrying a large number of pathogenic microorganisms. When subsequently transferred to indoor rearing, they generally exhibit slow growth, low immunity, and high deformity rates. Furthermore, artificial feed domestication is difficult and time-consuming. For example, fry hatched in outdoor ponds have a much higher probability of developing black bodies when transferred indoors than those hatched indoors. In addition, the traditional fry harvesting standard is 33 days after hatching (half of the fry have developed scales, oblique stripes on their sides, and cannibalism is observed). This not only prolongs the production cycle and increases risk but also misses the optimal feed transition period, leading to nutritional deficiencies and prolonged transition time. 3. High cost and uncertain effectiveness of regulation: Large amounts of bottom sediment improvers and beneficial bacteria (Bacillus, photosynthetic bacteria, etc.) are required in the later stages to regulate water quality and the fry's digestive system. However, this is costly and its effectiveness is greatly affected by the environment, failing to fundamentally solve the problem.

[0004] Indoor hatching can solve problems related to survival rate, quality, and disease in fish fry rearing. However, indoor hatching technology is demanding, production costs are high, and fry yield is low, failing to meet the needs of large-scale factory production and severely restricting the large-scale development of the aquaculture industry. Currently, the mainstream method for rearing fry is to pull pond fry to the pond after they reach the standard for release (i.e., after fin folding), then transfer them to indoor hatching for further rearing. This method cannot effectively overcome problems such as infectious diseases and damage during transport. Furthermore, many farmers purchase fry from other farmers, making it impossible to guarantee their health and safety; purchasing poor-quality fry often results in significant losses. Specifically, the typical technical process for indoor hatching includes: 1. Equipment and water treatment: using a 25m... 3 Each pool is equipped with 30 air stones 5cm from the bottom, a temperature management system, and 4 60W lights. The pool is disinfected one week in advance with 3000ml of bleaching powder containing 32% chlorine. The eggs are detoxified with sodium thiosulfate before being introduced into the pool. The water source must meet the GB11607 Fishery Water Quality Standard and the NY5052 Marine Aquaculture Water Standard, and be introduced into the pool after sedimentation and three-stage sand filtration. 2. Feed and Environmental Management: The night before fry feeding, fertilized oyster eggs are cultured and added to the water between 6-7 am the following day (when the fertilized eggs have developed to D-type larvae). Simultaneously, 50 million rotifers are introduced to assist with fry feeding. Subsequently, rotifers, *Daphnia mongolica*, *Artemia*, and exogenous fleas are fed according to the size of the fry. 260ml of concentrated *Chlorella vulgaris* is added to each pond daily for shade. Beneficial bacteria (EM bacteria, lactic acid bacteria, photosynthetic bacteria) and medications (organic acids, vibrio-based fungicides, and hymexazol) are introduced in the morning. Temperature is controlled at 26.5-27.5℃ (daily variation ≤1℃), and light is provided for 12 hours / day (intensity approximately 6000 lx). Feed is changed according to the standard that the mouth opening is twice the size of the live feed. 3. Indoor Nurturing and Grafting Facilities: Nurturing and fattening ponds are 6-8m² in area. 2 The pond is 1.3m deep (1m water depth), with a small flow of water. Natural light is used, and the light intensity is regulated by a shade net. Before the fry are released into the pond, they need to be visually observed and tested in the water for 24 hours (to ensure survival rate). The pond must be washed and disinfected. After being screened, the fry are raised in separate ponds and fed exogenous frozen plates and artificial feed until they stop eating. The problems with this model are: 1. High technical and equipment threshold: It requires high-end equipment such as ultrafiltration devices and full-spectrum lighting to purify seawater (remove bacteria and viruses) and meet the light requirements. The equipment, water, and electricity consumption is high, and operators need to have professional production knowledge. Training qualified hatchers is time-consuming and costly, forming a significant production barrier for ordinary fish farmers. 2. Low yield and poor efficiency: The indoor environment requires precise control, but space and resources are limited. The fry yield is much lower than that of outdoor ponds, and the cultivation cycle is long. It cannot meet the demand for large quantities of fry for large-scale grouper farming, and the economic benefits are lower than those of outdoor ponds.

[0005] In summary, traditional seedling raising methods rely on a single method, making it difficult to avoid the risk of increased pathogens and "pond annihilation" caused by the long-term accumulation of biomass during the later growth stages of juvenile fish. Moreover, even if the fry reach the target harvest size after the increase in pathogens, the fry will carry a large number of pathogenic microorganisms, which will affect the survival rate and quality of the fry after they are raised to adulthood. Summary of the Invention

[0006] To address the problems of insufficient quantity and poor quality of grouper fry, this invention provides a method for large-scale grouper fry breeding based on outdoor-indoor relay cultivation.

[0007] The purpose of this invention is to provide a method for large-scale grouper breeding based on outdoor-indoor relay cultivation, comprising the following steps:

[0008] S1. Outdoor pond preparation and disinfection: Select a black film pond with an area of ​​2-3 acres and a water depth of 1.8-2.5 meters as the initial hatching pond; after disinfecting and detoxifying the water, introduce it into the initial hatching pond for water cultivation, and monitor the water quality in real time;

[0009] S2. Outdoor fry hatching and phased feeding: Select viable grouper fertilized eggs and place them in hatching bags for incubation. On the third day of hatching, transfer them to the initial hatching pond. When the fry's mouth opening is less than 1000μm, feed them protozoa and rotifers. When the fry's mouth opening is greater than 1000μm but less than 1930μm, supplement the protozoa and rotifers with newly hatched Artemia, self-cultivated biological feed, and copepods cultivated in the outdoor feed pond. When the fry's mouth opening is greater than 1930μm but less than 2200μm, feed them self-cultivated copepods, newly hatched Artemia, and Daphnia mongolica. During this period, beneficial bacteria are applied daily. When 60% of the fry's mouth opening is greater than 2200μm, prepare for transfer.

[0010] S3. Indoor Seedling Pond Preparation and Water Treatment: PVC ponds are selected as indoor seedling ponds; the pond bottom is designed with a lower center and higher sides, and an inlet and outlet system is installed; the water for indoor seedling raising is sequentially filtered through coarse filtration, fine filtration, and ultraviolet disinfection, and then disinfected with sodium hypochlorite solution and detoxified with sodium thiosulfate before being introduced into the indoor seedling pond; the temperature control system is activated to ensure that the temperature difference between the indoor seedling pond water and the outdoor water is less than 2℃.

[0011] S4. Select qualified fry and pack them into fry bags, then transfer them indoors; disinfect them under a gentle stream of water before they enter the indoor nursery ponds;

[0012] S5. Cultivate, strengthen, and disinfect the biological baits Daphnia mongolica, Artemia, and copepods;

[0013] S6. Indoor phased feeding and feed transfer: After the fry are transferred to the indoor nursery pond, they are initially fed with Daphnia mongolica, copepods and newly hatched Artemia; when 60% of the fry have a mouth gape greater than 3.5 mm, they are fed with Daphnia mongolica and Artemia medium; when 60% of the fry have a mouth gape greater than 5 mm, feed acclimatization is started, during which a combination of live feed and artificial feed is used. The live feed includes Daphnia mongolica and adult Artemia.

[0014] S7. Control the density of fish fry during indoor fry rearing and carry out daily management.

[0015] Preferably, the walls of the initial hatching tank are guaranteed to be undamaged, the bottom of the tank is a structure that slopes towards the center of the tank and the center of the tank is watertight, and it is equipped with an inlet and drainage system and an oxygenation device; after the initial hatching tank is exposed to the sun, it is disinfected with bleaching powder and then rinsed with clean water 2-3 times to remove residual disinfectant;

[0016] The water quality indicators must meet the following conditions: water temperature above 23℃; pH value between 7.8 and 8.3; dissolved oxygen content not less than 5 mg / L; salinity between 26 and 28%.

[0017] Preferably, in step S2, when the mouth slit of the larvae is less than 1000μm, the larvae are fed once a day to maintain a rotifer density of 3-5 rotifers / mL in the pond.

[0018] When the mouth opening of the larvae is greater than 1000μm and less than 1930μm, feed them once a day; self-cultivated biological food includes rotifers and copepod larvae;

[0019] When the mouth gape of the fry is greater than 1930μm and less than 2200μm, feed them once a day;

[0020] Beneficial bacteria include Bacillus, lactic acid bacteria, EM bacteria, and photosynthetic bacteria; Bacillus is sprayed into the pool once a day, and lactic acid bacteria, EM bacteria, and photosynthetic bacteria are sprayed every other day.

[0021] Preferably, the indoor seedling tank is 1.2-1.5m deep, and the water depth is controlled at 1m during seedling cultivation; the drainage system includes bottom drainage and surface drainage, with the surface drainage pipe located in the center of the tank at a height of 1.2-1.5m, and the drainage pipe is wrapped with a 60-100 mesh silk screen; the water inlet is fitted with a pure cotton filter bag with a pore size of 50-80μm, and 26-30 air stones are evenly arranged in the indoor seedling tank and evenly distributed along the tank wall. At the same time, the indoor seedling tank is equipped with a pure oxygen supply device.

[0022] Preferably, the coarse filtration in step S3 is sand filtration in a sand filter tank, with quartz sand as the filter media and a particle size of 0.5~1mm; the ultrafiltration is carried out using an ultrafiltration device with an ultrafiltration membrane pore size of 0.01~0.1μm; the ratio of sodium thiosulfate solution to sodium hypochlorite solution is 10g:100ml.

[0023] One day before the transfer, test the water quality in the indoor nursery pond to ensure dissolved oxygen is 6-10 mg / L, pH is 8.2-8.4, ammonia nitrogen is below 0.05 mg / L, and nitrite is below 0.05 mg / L. After meeting the standards, maintain the water circulation state and wait for the fry to be transferred.

[0024] Preferably, in step S4, qualified fry are fry that swim freely, react quickly, are of uniform size, have no deformities, and have normal body color.

[0025] Before transferring the fish fry, add stress medication to the initial hatching tank to prevent the fish fry from experiencing stress due to environmental changes;

[0026] After transferring the fish fry indoors, first pour them into a small basket with a slight flow of water for disinfection. The disinfectant is prepared by mixing formalin solution, copper sulfate, and fresh water. After disinfection, distribute the fish fry evenly into the indoor nursery pond, open the inlet and outlet valves to maintain a continuous slight flow of water, and at the same time increase the oxygen supply appropriately.

[0027] Preferably, in step S5, the cultivation and treatment of Artemia includes: pre-stocking dormant Artemia eggs indoors and refrigerating them; using 1 ton of water for incubation and cultivation, incubating at a ratio of 1 ton of water to 1.5 kg of dormant Artemia eggs; controlling the water temperature above 26℃, filtering and collecting Artemia after 20-30 hours of incubation, rinsing the Artemia with fresh water until there are no excess eggshells; temporarily storing the Artemia in the prepared water, strengthening disinfection, and then using it for later use.

[0028] The expansion and processing of Daphnia mongholica includes: expanding Daphnia mongholica two weeks in advance, collecting Daphnia mongholica after expansion, washing to remove impurities, and then strengthening it for later use.

[0029] The treatment and breeding of copepods include: one week in advance, detoxifying and culturing copepods in flowing water, adding beneficial bacteria, drugs and povidone-iodine daily for disinfection and sterilization, and feeding them after a week of disinfection and sterilization and passing the test.

[0030] Preferably, in step S6, the initial feeding ratio is as follows: the feeding amounts of Daphnia mongolica, newly hatched Artemia, and copepods are 180-220g, 90-110g, and 90-110g respectively for 10,000 fish fry; during the feeding process, the input amount of Daphnia mongolica and newly hatched Artemia increases by 5% daily, while the input amount of copepods remains unchanged, and the total amount of feed increases by 5% daily.

[0031] When the mouth gape of the fish fry is greater than 3.5 mm, the feeding amount of Daphnia mongholicus and Artemia is 280~320g and 190~210g respectively for 10,000 fish fry.

[0032] When the mouth cleft of the fish fry is greater than 5mm, the initial feeding amount of Daphnia mongholicus and adult Artemia is 300-400g and 100-150g per 10,000 fish fry, respectively; the amount of live feed is reduced by 15% per day; the initial feeding amount of artificial feed is 20g per 10,000 fish fry, and then increased by 30g per 10,000 fish fry per day.

[0033] Preferably, in step S6, the initial feeding ratio is as follows: the feeding amount for Daphnia mongolica, newly hatched Artemia and copepods is 200g, 100g and 100g respectively for 10,000 fish fry.

[0034] When the mouth cleft of the fish fry is greater than 3.5 mm, the feeding amount of Daphnia mongholicus and Artemia is 300g and 200g respectively for 10,000 fish fry.

[0035] When the mouth cleft of the fish fry is greater than 5mm, the initial feeding amount of Daphnia mongholicus and adult Artemia is 350g and 130g respectively for 10,000 fish fry.

[0036] Preferably, in step S7, the stocking density of fish fry in the indoor nursery pond is 3000-4000 fish / meter. 3 On the day the fish fry are introduced into the indoor nursery pond, feed them a small amount of feed; change the water in the nursery pond every evening for 12 hours, and change 28-32% of the total water volume in the nursery pond; add anti-stress medicine to the pond half an hour before changing the water; and perform bottom suction every 7 days.

[0037] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0038] 1. For grouper, the method of this invention allows for an outdoor-to-indoor seedling rearing and feed transfer time of approximately 45 days. After rearing, the disease incidence rate is low, the survival rate is high, the fry yield is large, the seedling quality is high, and the feed transfer speed is fast, meeting the requirements for rapid seedling rearing. This helps solve the problems of high fry yield but poor fry quality in outdoor ponds and high-quality but low-quantity fry in indoor workshops. It is conducive to expanding the scale of the grouper aquaculture industry and its industrialization, thus promoting the development of the grouper aquaculture industry.

[0039] 2. This invention involves three treatments of seawater and indoor self-cultivation and fortification of the live feed, improving its safety and supplementing its nutrition. A tiered feeding method using a variety of live feeds, including Daphnia mongolica, Artemia, and copepods, combined with artificial feed, meets the nutritional needs of the fry while increasing their feeding diversity, promoting rapid growth of grouper juveniles, effectively improving their disease resistance, and enhancing their environmental adaptability. Adding live feed and artificial feed in the correct proportions improves feed utilization, reduces water pollution and material loss, and significantly improves the survival rate of the fry.

[0040] 3. Transfer fish fry raised in outdoor ponds to the workshop in advance, and conduct observation, water testing, quarantine, and disinfection of the fish fry to keep external viruses out of the workshop and avoid the risks caused by the incomplete replacement of water in outdoor ponds for a long time, so as to achieve the health of fish fry in indoor workshops.

[0041] 4. Subsequent cultivation is carried out in an indoor workshop, with a rationalized feeding ratio and a variety of live feed types. Without altering the environment, the fish fry are rapidly transitioned from live feed to purely artificial feed, accelerating the transition and effectively ensuring their growth and nutritional needs are met, while reducing the incidence of gill rot and emaciation. This achieves the goal of rapid feed transition. Attached Figure Description

[0042] Figure 1 This is a flowchart of a method for large-scale grouper breeding based on outdoor-indoor relay cultivation according to an embodiment of the present invention. Detailed Implementation

[0043] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0045] This invention provides a method for large-scale grouper breeding based on outdoor-indoor relay cultivation, comprising the following steps:

[0046] S1. Preparation and Disinfection of Outdoor Ponds

[0047] S101. Basic conditions for the initial hatching pond: Select a black film pond with an area of ​​2-3 acres and a water depth of 1.8-2.5 meters as the initial hatching pond for grouper. The pond walls must be intact, the pond bottom must be designed with a slope towards the center and the center must be leak-proof, and a convenient water inlet and drainage system must be provided. At the same time, equip the hatching pond with one dedicated hatching device and two waterwheel aeration devices; in addition, set up a separate pond of suitable size as a live feed cultivation pond for subsequent supplementation of live feed for the fry.

[0048] S102. Pre-treatment of the initial hatching tank: First, drain the residual water in the tank, rinse the tank walls and bottom with a high-pressure water gun until there are no obvious impurities, and then expose the tank to the sun for 6-8 days; after the sun exposure, use bleaching powder with a chlorine content of 30-35% and mix it with the water to be disinfected in the hatching tank in a total amount of 50kg, let it stand for disinfection for 20-30 hours, after the disinfection is completed, drain the disinfected water, rinse the tank with clean water 2-3 times to remove residual disinfectant;

[0049] S103. Water Preparation and Quality Control: Disinfected and detoxified reserve water is introduced into the prepared hatching pond, maintaining a water depth of 1.2-1.5m. The water preparation process is initiated: a fermented mixture of fishmeal and brewer's yeast (or amino acid peptide fertilizer) is sprinkled into the pond at a rate of 50-80g per cubic meter of water. This process continues for 3-7 days, during which the reproduction of protozoa and rotifers in the pond is observed daily. When the rotifer density reaches 5-8 individuals / mL, the appropriate time for egg introduction is determined. During water preparation and subsequent hatching, water quality indicators must be monitored in real time to ensure the following conditions are met: water temperature maintained above 23℃; pH value controlled between 7.8 and 8.3; dissolved oxygen content not less than 5mg / L (controlled by a waterwheel aeration equipment); salinity maintained at 26-28%; and ammonia nitrogen, nitrite, hydrogen sulfide, and heavy metal content all below the limits specified in GB 11607-2008 Fisheries Water Quality Standard.

[0050] S2. Outdoor fry hatching and phased feeding

[0051] S201. Incubation of Fertilized Eggs: Select brightly colored, deformed, and highly active grouper fertilized eggs and place them in an incubation bag. A shade net should be erected above the incubation bag to prevent direct sunlight. Initially, the incubation bag should be filled with 4-6 g / m³ of water. 3 Disinfect the surface of the hatching bag with potassium permanganate solution, rinse it clean, and then soak the hatching bag in the hatching pool water for 12-20 minutes. Then slowly pour the fertilized eggs into the hatching bag. Adjust the air supply so that the fertilized eggs can be lifted evenly without sinking to the bottom. Take random samples with a beaker every 2-3 hours to observe the hatching progress. After the fry hatch, take one beaker of fry samples from each of the four corners of the hatching bag to count and estimate the total number of fry.

[0052] S202. Staged Feeding Management: On the third day of hatching, when the larvae have developed mouths and eye spots and can swim freely and feed, the hatching bags should be opened: One hour before opening the bags, sprinkle VC solution at a rate of 500g per acre of hatching pond to alleviate the stress response of the larvae. Then, open the hatching bags and allow the larvae to enter the hatching pond naturally. Adjust the feeding plan according to the size of the larvae's mouths, as follows:

[0053] (1) When the mouth opening of the fry is less than 1000μm: feed protozoa and rotifers 4-6 times a day to maintain a rotifer density of 3-5 rotifers / mL in the pond; at the same time, sprinkle a small amount of fishmeal fermented fertilizer to supplement the biological nutrition of the feed; sprinkle Bacillus subtilis into the pond once a day (at a dosage of 0.4-0.6g / mL). 3 The next day, spray with lactic acid bacteria (0.2~0.4g / m³). 3 EM bacteria (0.3~0.5g / m³) 3 ), photosynthetic bacteria (0.5~0.7g / m³) 3 );

[0054] (2) When the mouth gape of the larvae is greater than 1000μm and less than 1930μm: In addition to protozoa and rotifers, supplement the feeding with newly hatched brine shrimp, self-cultivated biological feed (rotifers, copepod larvae) and copepods cultivated in outdoor feed ponds, and feed them 5 to 7 times a day; the types and frequency of beneficial bacteria feeding remain unchanged.

[0055] When the mouth gape of the larvae is greater than 1930μm and less than 2200μm: stop feeding protozoa, and mainly feed self-bred copepods, newly hatched Artemia and Daphnia mongolica, 6-8 times a day, and keep the types and frequency of beneficial bacteria feeding unchanged.

[0056] Continuously monitor the mouth development of the larvae. When 60% of the larvae have a mouth opening greater than 2200μm (corresponding to newly hatched larvae at 21-23 days old), stop outdoor rearing and enter the indoor transfer preparation stage.

[0057] S3. Preparation of Indoor Seedling Ponds and Water Treatment

[0058] S301. Water tank equipment configuration: 25m 3 The circular blue PVC ponds are used as indoor seedling beds, with a depth of 1.2~1.5m, and the water depth is controlled at 1m during normal seedling cultivation. The bottom of the pond is designed with a lower center and a higher perimeter, equipped with a dual drainage system of bottom and surface drainage to facilitate the discharge of impurities and feces. The inlet of the seedling pond is covered with a pure cotton filter bag (pore size 50~80μm), and the central drain pipe is set at a height of 1.3m, with a 60~100 mesh silk screen covering the drain pipe. 26~30 air stones are evenly arranged in each seedling pond, about 5cm from the bottom of the pond, and distributed along the perimeter of the pond wall, with an interval of about 1m between adjacent air stones. At the same time, each seedling pond is equipped with a pure oxygen supply device.

[0059] S302. Three-stage water treatment: The water used for indoor seedling raising adopts the unified water supply of the industrial park and needs to be treated in three stages before use: (1) The seawater is first filtered through a sand filter tank (the filter material is quartz sand with a particle size of 0.5-1mm) to remove suspended impurities with a particle size greater than 10μm in the water; (2) The seawater after sand filtration enters the workshop ultrafiltration equipment (ultrafiltration membrane pore size 0.01-0.1μm) for filtration, and at the same time passes through an ultraviolet disinfection device (power 30W, irradiation time 30s) to remove bacteria and viruses in the water; (3) The seawater after ultrafiltration disinfection is transferred to the storage tank, and 200ml of sodium hypochlorite solution with a concentration of 8~15% is added per cubic meter of water for disinfection. After standing for 10~15 hours, sodium thiosulfate is added to detoxify at a ratio of 10g:100ml of sodium thiosulfate solution to sodium hypochlorite solution. After detoxification, the residual chlorine content of the water is tested. After confirming that the residual chlorine is 0mg / L, the water is introduced into the seedling pond.

[0060] S303. Water Pre-conditioning: Seven days before the outdoor fry transfer, introduce the three-stage treated water into the indoor nursery pond, activate the temperature control system, and adjust the nursery pond water temperature to be consistent with the outdoor hatching pond water temperature (error not exceeding 2℃); one day before the transfer, test the nursery pond water quality indicators again to ensure that the water temperature is stable at 26.5~27.5℃, dissolved oxygen 6~10mg / L, pH value 8.2~8.4, ammonia nitrogen below 0.05mg / L, and nitrite below 0.05mg / L. After meeting the standards, maintain the water circulation state and wait for the fry to be transferred.

[0061] S4. Fry selection, quarantine and transfer

[0062] S401. Larval Screening and Quarantine: From the initial hatching ponds, randomly select 100 larvae from each pond and place them in plastic basins filled with seawater. Visually inspect the larvae to ensure they swim freely, react quickly, are of uniform size, have no deformities, and have normal body color. Select larvae that meet the appearance requirements. Pack the qualified larvae into fry bags (50 larvae per bag, with seawater filling 1 / 3 of the bag), label them with the corresponding pond number, and take them back to the indoor workshop. Place the fry bags in the nursery pond water and conduct a 24-hour water test under oxygen-free conditions. The larval survival rate should not be less than 90%. At the same time, randomly select another 100 larvae from each pond and send them to the laboratory for testing to check for pathogens such as Vibrio and viruses. Larvae that are confirmed to be free of pathogens are qualified for transfer.

[0063] S402. Fry Transfer Procedures: Transfer should be carried out on sunny or partly cloudy days. Before transfer, disinfect catching tools (such as hand nets and holding tanks) (e.g., soak in a 5% povidone-iodine solution for 30 minutes, then air dry before use) to prevent disease transmission. Simultaneously, add stress medication to the early-stage hatching tank (e.g., sprinkle with vitamin C solution at a dosage of 0.3 g / m³). 3To prevent stress on the fry due to environmental changes, the water level in the outer pond was lowered to 80cm. Harvesting began after the hatching pond water level dropped to 80cm, with quick and steady movements to avoid oxygen deprivation in the fry due to improper handling. Qualified fry were temporarily stored in suitable containers, ensuring their vitality and avoiding squeezing or oxygen deprivation (no more than 500 fry per container, with continuous oxygenation).

[0064] Aeration and disinfection were carried out on the water inside the waterwheel beforehand; an appropriate amount of anti-stress medication (such as glucose, at a dosage of 2g / m³) was added to the waterwheel. 3 To further prevent stress on the fry during transport; before transferring the outdoor fry to the transport vehicle, feed the fry a small amount of live feed to avoid the fry spitting out feed and polluting the water and reducing dissolved oxygen during transport, thereby reducing fry loss; maintain stable water temperature during transport and keep the journey within 2 hours to ensure the vitality of the fry.

[0065] After transferring the fish fry to the indoor workshop, place them next to the nursery ponds and pour them into small baskets with an inner diameter of 0.5 meters and an inner height of 0.15 meters. Keep the baskets in a state of slight water flow (this serves two purposes: first, to remove the dirty water from the original pond carried by the fish fry, and second, to disinfect the fish fry). The disinfectant is prepared by mixing 100 ppm formalin solution, 1 ppm copper sulfate, and fresh water. Soak the fish fry in the disinfectant for about 30 seconds. After disinfection, distribute the fish fry evenly into each indoor nursery pond. After the fish fry have been released, promptly open the inlet and outlet valves of each nursery pond to maintain a continuous slight water flow, while appropriately increasing the oxygen supply to provide a suitable initial growth environment for the fish fry.

[0066] S5. Preparation and processing of live bait

[0067] (1) Cultivation and treatment of Artemia: Prepare Artemia dormant eggs in advance indoors and store them in a refrigerator; use 1 ton of water for incubation and cultivation, and incubate them at a ratio of 1 ton of water to 1.5 kg of Artemia dormant eggs; control the water temperature above 26℃, collect the eggshells after 24 hours of incubation, use a combination of 120 and 200 mesh to filter and collect the Artemia, rinse the Artemia with fresh water until there are no excess eggshells; temporarily store the Artemia in the prepared water, strengthen disinfection and use it for later use.

[0068] (2) Expansion and treatment of Daphnia mongholica: Daphnia mongholica was expanded two weeks in advance in a 20 cubic meter water body. After expansion, Daphnia mongholica was collected, cleaned to remove impurities, and then placed into a 1 cubic meter water body prepared in advance for enhancement. After enhancement, it was used for later use.

[0069] (3) Treatment and breeding of copepods: Purchase high-quality copepods and carry out detoxification and running water culture of copepods one week in advance. Add beneficial bacteria, drugs and povidone-iodine every day for disinfection and sterilization. Feed them after passing the test one week after disinfection.

[0070] One day before feeding Daphnia mongolica, Artemia, and copepods, the live feed was temporarily held in 1000L clean seawater incubation tanks, with the temperature controlled at 26~29℃. The temperature difference between the tank and the fishpond was controlled to be no more than 2℃ to prevent the live feed from being stressed and dying quickly after being released into the pond. Air stones were added to ensure dissolved oxygen was greater than 6mg / L, and the amount of live feed temporarily stored in each tank was less than 2500g. Artemia, copepods, and Daphnia mongolica were temporarily incubated in ultrafiltered seawater for enhanced nutrition, disinfected with povidone-iodine for 10 minutes, and then washed before feeding.

[0071] S6. Indoor phased feeding and feed transfer

[0072] (1) Initial feeding (mouth crack not reaching 3.5mm): After the fry are transferred to the indoor nursery pond, they are initially fed with Daphnia mongolica, copepods and newly hatched Artemia. The feeding ratio is calculated according to the number of fry: the feeding amount of Daphnia mongolica, newly hatched Artemia and copepods is 180~220g, 90~110g and 90~110g respectively for 10,000 fry; during the feeding process, the amount of Daphnia mongolica and newly hatched Artemia increases by 5% every day, the amount of copepods remains unchanged, and the total amount of feed increases by about 5% every day to ensure that the fry get enough nutrition.

[0073] (2) Stage with mouth cleft greater than 3.5mm: When it is observed that 60% of the fry have mouth cleft greater than 3.5mm, adjust the feeding plan and feed only Daphnia mongolica and Artemia spp. According to the number of fry, the amount of Daphnia mongolica and Artemia spp. in each nursery pond is 280~320g and 190~210g respectively for 10,000 fry. Continue feeding until the fry's mouth cleft reaches 5mm.

[0074] (3) Feeding and transfer during the stage of cracks greater than 5mm

[0075] Feed acclimatization initiation conditions: When 60% of the fry have mouths with a crack greater than 5mm, feed acclimatization should be initiated. Before acclimatization, the fry in the nursery pond should be sorted and grouped into small baskets according to their size to avoid them biting each other due to large size differences, and to facilitate rapid feeding.

[0076] Specific procedures for acclimatization: During acclimatization, the surrounding environment should be quiet, and personnel are strictly prohibited from walking around or making loud noises. A perforated floating frame (0.3m x 0.3m) should be set up in each fry pond to gather the fish. After wetting the artificial feed, knead it into an oval shape and put it in the fry gathering area one pellet at a time. Only put in the next pellet after confirming that the fry have eaten. Acclimatization should be carried out during the day, and each acclimatization session should last for 12 hours. After acclimatization, use a water pump to remove any uneaten feed from the bottom of the pond to prevent water pollution.

[0077] Feeding ratio and adjustment: During the acclimatization period, a combination of live feed and artificial feed is used. The initial feeding amount of Daphnia mongholicus and adult Artemia worms in each fry pond is 300-400g and 100-150g respectively for 10,000 fry. The amount of live feed is reduced by 15% per day, and the initial feeding amount of artificial feed is 20g per 10,000 fry, which is then increased by 30g per 10,000 fry per day. Specifically, artificial feed is selected according to the economic value of the grouper species. High-value grouper (such as leopard gill spiny grouper and red nine-spined grouper) uses the Japanese imported Yubao series feed, while ordinary-value grouper (such as tiger dragon hybrid grouper and blue melon seed grouper) uses Yizikou floating feed.

[0078] Feeding time and environmental control: Start feeding live feed and artificial feed at 6-7 am every day to ensure that the fry feed under sufficient light conditions; turn off the lights above the frying pond at 5:30 pm and turn up the water inlet switch to discharge excess live feed and impurities at the bottom of the frying pond through the central pipe mesh. At this time, the central pipe needs to be replaced with a 20-mesh net; add 4g of the light-blocking agent Youcai Le to each frying pond every day to control the water visibility at about 80cm during feeding.

[0079] S7. Fish fry density control and daily management in indoor nursery ponds

[0080] Density control: The stocking density of fish fry needs to be determined comprehensively based on the conditions of the nursery pond (including supporting equipment), the initial size of the fish fry, the expected size at harvest, and the nursery and fry rearing techniques. If the stocking size of the fish fry is 1.2-2 cm and the expected size at harvest is 3-5 cm, the stocking density is usually 3000-4000 fish / meter. 3 It is advisable to stock each of the 25 cubic meter indoor nursery ponds with 60,000 fish fry.

[0081] Routine operations: On the day the fry are introduced into the indoor nursery pond, feed them a small amount of feed; change the water in the nursery pond every evening, replacing 28-32% of the total water volume. The water change should start at night and last for 12 hours. Add anti-stress medication to the pond half an hour before the water change; perform bottom sifting every 7 days to remove impurities and feces from the bottom of the pond. Add anti-stress medication half an hour before bottom sifting to reduce stress on the fry.

[0082] Example 1

[0083] This embodiment provides a method for large-scale grouper breeding based on outdoor-indoor relay cultivation, wherein the specific parameters for each step include:

[0084] In step S1, a black film pond with an area of ​​2.5 acres and a water depth of 2 meters is selected as the initial hatching pond for grouper. First, the residual water in the pond is drained, and the pond walls and bottom are rinsed with a high-pressure water gun until there are no obvious impurities. Then, the pond is exposed to the sun for 7 days. After the sun exposure, bleaching powder with a chlorine content of 32% is mixed with the water to be disinfected in the hatching pond at a total amount of 50 kg. The mixture is left to stand for 24 hours for disinfection. After the disinfection is completed, the disinfected water is drained, and the pond is rinsed with clean water 2-3 times to remove residual disinfectant.

[0085] In step S2, use 5g / m 3 Disinfect the surface of the hatching bags with potassium permanganate solution, rinse them clean, and then soak them in the hatching tank water for 15 minutes. When feeding in stages, sprinkle Bacillus subtilis (at a dosage of 0.5g / m³) into the tank once a day. 3 The next day, spray with lactic acid bacteria (0.3g / m²). 3 EM bacteria (0.4g / m) 3 ), photosynthetic bacteria (0.6g / m 3 );

[0086] In step S3, the drain pipe of the seedling pond is wrapped with an 80-mesh silk screen; 28 air stones are evenly arranged in each seedling pond; the seawater after ultrafiltration and disinfection is transferred to the storage pond, and 200ml of 10% sodium hypochlorite solution is added per cubic meter of water for disinfection, and the pond is left to stand for 12 hours; ensure that the difference between the indoor and outdoor water temperatures is less than 1℃.

[0087] In step S4, the stress medication is a vitamin C solution; the anti-stress medication is glucose.

[0088] In the initial feeding stage of step S6, the feeding amounts of Daphnia mongolica, newly hatched Artemia salina, and copepods are 200g, 100g, and 100g respectively for 10,000 fish fry; in the stage where the mouth opening is greater than 3.5mm, the feeding amounts of Daphnia mongolica and Artemia salina are 300g and 200g respectively for 10,000 fish fry; in the stage where the mouth opening is greater than 5mm, the initial feeding amounts of adult Daphnia mongolica and Artemia salina are 350g and 130g respectively for 10,000 fish fry.

[0089] In step S7, the daily water exchange volume is 30% of the total water volume in the seedling pond.

[0090] Example 2

[0091] This embodiment provides a method for large-scale grouper breeding based on outdoor-indoor relay cultivation, wherein the specific parameters of each step are the same as in Embodiment 1.

[0092] Example 3

[0093] This embodiment provides a method for large-scale grouper breeding based on outdoor-indoor relay cultivation, wherein the specific parameters of each step are the same as in Embodiment 1.

[0094] Comparative Example 1

[0095] The difference from Examples 1, 2, and 3 is that: seedlings are raised outdoors only, without the stage of moving them indoors for cultivation.

[0096] Comparative Example 2

[0097] The difference from Examples 1, 2, and 3 is that: the outdoor-to-indoor method is used for seedling cultivation, mixed feeding is not used, and a single type of Mongolian naked-bellied daphnia feed is fed every day, with the feeding amount increased by 5% per day.

[0098] Comparative Example 3

[0099] The difference from Examples 1, 2, and 3 is that the seedlings are raised using an outdoor-to-indoor method, without feeding them self-cultivated biological feed, and relying on pure exogenous biological feed.

[0100] Comparative Example 4

[0101] The difference from Examples 1, 2, and 3 is that the seedlings were raised by transferring from outdoor to indoor methods and were directly acclimatized to feed, without using the method of gradually increasing the proportion of artificial feed for acclimatization.

[0102] Application Example 1

[0103] In March 2024, seedlings were raised according to the methods of Examples 1-3 and Comparative Examples 1-4, and were designated as study groups 1-7 respectively. After the seedling raising was completed, the survival rate, disease incidence, and average size of the tiger-dragon hybrid fry in study groups 1-7 were statistically analyzed. The results are shown in Table 1.

[0104] Table 1. Seedling status of Tiger Dragon Hybrid Spots

[0105]

[0106] The results showed that all fry raised in the study group met the standards for market release and were successfully transferred to feed. However, indoor fry rearing resulted in a low disease rate, high survival rate, good fry vitality, and rapid transfer to feed. Comparative Examples 1-4 showed higher disease rates, lower survival rates, significantly reduced fry yield, and slower transfer to feed. Comparative Examples 1 and 3 demonstrate that water quality and feed safety are crucial for the survival rate of grouper. Comparative Examples 2 and 4 indicate that nutritional deficiencies and improper feed combinations may have caused intestinal damage, hindering effective and rapid nutrient absorption and failing to meet the requirements for rapid fry transfer.

[0107] Application Example 2

[0108] The tiger-dragon hybrid grouper fry obtained in Examples 1-3 and Comparative Examples 1-4 were used in a culture trial at the Wenchang Grouper Aquaculture Base in Hainan Province in April 2024. Each experimental group was stocked with 1,000 fry, and daily management was carried out according to factory-style aquaculture technical specifications. After 180 days of culture, adult fish were harvested, and survival rate, disease rate, and average weight were recorded. The results are shown in Table 2.

[0109] Table 2. Aquaculture of Tiger-Dragon Hybrid Spotted Spots

[0110]

[0111] The results showed that, compared with comparative examples 1-4, the survival rate of tiger arowana hybrids cultured in examples 1-3 was higher, the disease rate was lower, and the adult fish weight was higher. This indicates that the fish fry obtained from examples 1-3 were used for culture, resulting in better quality, better resistance, and higher yield of adult fish.

[0112] Application Example 3

[0113] In October 2024, fry were raised according to the methods of Examples 1-3 and Comparative Examples 1-4, and were designated as study groups 1-7 respectively. After the fry rearing was completed, the survival rate, disease incidence, and average size of the leopard-gill spiny perch fry in study groups 1-7 were statistically analyzed. The results are shown in Table 3.

[0114] Table 3. Aquaculture status of Leopard Gill Bass

[0115]

[0116] The results showed that, compared with outdoor rearing, indoor rearing of leopard-gill sea bass resulted in lower disease incidence, higher survival rates, better fry vitality, and faster transition to new feed. However, ratios 1-4 showed higher disease incidence, lower survival rates, significantly reduced fry yield, and slower transition to new feed, failing to meet the requirements for rapid rearing and transition. Furthermore, compared with the tiger bream hybrid, the indoor rearing survival rate of leopard-gill sea bass was lower.

[0117] Application Example 4

[0118] In January 2025, seedlings were raised according to the methods of Examples 1-3 and Comparative Examples 1-4, and were designated as study groups 1-7 respectively. After the seedling raising was completed, the survival rate, disease incidence, and average size of the red snapper fry in study groups 1-7 were statistically analyzed. The results are shown in Table 4.

[0119] Table 4. Aquaculture of Red Nine-Spined Bass

[0120]

[0121] The results showed that, compared with outdoor rearing, indoor fry rearing resulted in lower disease rates, higher survival rates, better fry vitality, and faster transition to new feed. However, compared with the Tiger Dragon hybrid and Leopard Gill spiny perch, the indoor fry survival rate of the Red Nine-Spined Perch was lower.

[0122] In summary, this invention develops a relay-style large-scale fry breeding method by changing the single fry breeding approach. This method combines the advantages of outdoor pond hatching (low cost, high efficiency, simple operation, and large-scale early-stage fry production) with the advantages of indoor workshop fry rearing (high controllability, healthy fry, and easy management in the later stages). Outdoor ponds employ strict and safe water and insect culture practices, rational fry feeding, and fry are transferred to the indoor workshop in advance according to the fry mouth-opening standard. Indoor aquaculture conditions are improved through industrial-grade ultrafiltration of seawater, daily control of lighting intensity, increased dissolved oxygen levels, and daily water quality monitoring. Refined management includes separate fry feeding in separate ponds, strict control of the amount of live feed given at each meal, daily large-scale water changes, advance expansion and disinfection of live feed, and timely administration of biological animal health products. At the same time, we strictly control the feeding and rearing process, select reasonably priced feed, set up floating frames to gather fish, manually knead the feed, and set fixed long feeding times every day to save the time of transferring the fish fry to feed, improve the survival rate of the fish fry, improve the quality of the seedlings, reduce the occurrence of diseases, and achieve a breakthrough in both the quantity and quality of fish fry, ultimately providing a reliable seedling guarantee for large-scale aquaculture.

[0123] This study innovatively proposes a combined method of hatching and rearing in indoor workshops and outdoor ponds, integrating the advantages and disadvantages of both. Initial hatching is conducted in outdoor ponds to ensure a sufficient number of fry. Around 20 days after hatching, when the fry are about to complete finning and 60% of the fry have a mouth opening greater than 2200μm, they are transferred to the indoor workshop for separate rearing and feeding in a small indoor water volume. Improved rearing conditions include industrial-grade ultrafiltration of seawater, daily control of lighting intensity, increased dissolved oxygen levels, and daily water quality monitoring. Refined management is implemented, including separate feeding of fry in different ponds, strict control of the amount of live feed given at each meal, large-scale water changes daily, advance cultivation and disinfection of live feed, and timely administration of animal health products. Simultaneously, strict quality control is maintained during the rearing stage, using reasonably priced feed, setting up floating frames to gather fish, and manually kneading feed. Fixed-time feeding periods are implemented daily to save time on fry transfer, ultimately achieving a breakthrough in both the quantity and quality of fry.

[0124] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0125] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for large-scale grouper breeding based on outdoor-indoor relay cultivation, characterized in that: Includes the following steps: S1. Outdoor Pond Preparation and Disinfection: Select a black film pond with an area of ​​2-3 mu (approximately 0.16-0.2 hectares) and a water depth of 1.8-2.5 meters as the initial hatching pond; after disinfection and detoxification, introduce the water into the initial hatching pond for water cultivation, and monitor the water quality in real time; ensure that the pond walls are undamaged, the pond bottom has a slope towards the center and the center is leak-proof, and equip it with an inlet and outlet drainage system and aeration equipment; after sun exposure, disinfect the initial hatching pond with bleaching powder, and then rinse it with clean water 2-3 times to remove residual disinfectant; the water quality indicators should meet the following conditions: water temperature above 23℃; pH value between 7.8 and 8.3; dissolved oxygen content not less than 5 mg / L; salinity 26-28%; S2. Outdoor fry hatching and phased feeding: Select viable grouper fertilized eggs and place them in hatching bags for incubation. On the third day of hatching, transfer them to the initial hatching pond. When the fry's mouth opening is less than 1000μm, feed them protozoa and rotifers 4-6 times daily, maintaining a rotifer density of 3-5 rotifers / mL in the pond. When the fry's mouth opening is greater than 1000μm but less than 1930μm, supplement the protozoa and rotifer feed with newly hatched brine shrimp, self-cultivated biological feed, and copepods cultivated in the outdoor feed pond. Feed 5-7 times daily; self-cultivated biological feed includes rotifers and copepod larvae; when the larvae's mouth opening is greater than 1930μm but less than 2200μm, feed them self-cultivated copepods, newly hatched Artemia, and Daphnia mongolica 6-8 times daily; during this period, apply beneficial bacteria daily; beneficial bacteria include Bacillus, lactic acid bacteria, EM bacteria, and photosynthetic bacteria; apply Bacillus once daily to the pond, and apply lactic acid bacteria, EM bacteria, and photosynthetic bacteria every other day; when 60% of the larvae's mouth opening is greater than 2200μm, prepare for transfer. S3. Preparation and water treatment of indoor seedling ponds: PVC ponds are selected as indoor seedling ponds. The depth of the indoor seedling ponds is 1.2~1.5m, and the water depth is controlled at 1m during seedling cultivation. The bottom of the pond is designed with a structure that is lower in the middle and higher around the edges, and a water inlet and drainage system is set up. The water used for indoor seedling cultivation is successively filtered by coarse filtration, ultrafiltration and ultraviolet disinfection, and then disinfected by sodium hypochlorite solution and detoxified by sodium thiosulfate before being introduced into the indoor seedling ponds. Activate the temperature control system to keep the temperature difference between the indoor and outdoor water in the seedling tank below 2°C; the ratio of sodium thiosulfate to sodium hypochlorite solution is 10g:100ml; the drainage system includes bottom drainage and surface drainage, with the surface drainage pipe located in the center of the tank at a height of 1.2~1.5m, and the drainage pipe is wrapped with a 60~100 mesh silk screen. The inlet is fitted with a pure cotton filter bag with a pore size of 50-80μm. 26-30 air stones are evenly distributed in the indoor nursery pond, along the surrounding walls. A pure oxygen supply device is also provided for the indoor nursery pond. The coarse filtration is done with a sand filter tank, using quartz sand as the filter media with a particle size of 0.5-1mm. The ultrafiltration is done with an ultrafiltration membrane with a pore size of 0.01-0.1μm. One day before transfer, the water quality in the indoor nursery pond is tested to ensure dissolved oxygen is 6-10mg / L, pH is 8.2-8.4, ammonia nitrogen is below 0.05mg / L, and nitrite is below 0.05mg / L. After meeting the standards, the water circulation is maintained, awaiting the transfer of fry. S4. Select qualified fry, pack them into fry bags, and transfer them indoors; Disinfected under a gentle flow of water before being placed in the indoor fry rearing pond; qualified fry are those that swim freely, react quickly, are of uniform size, have no deformities, and have normal body color; stress medication is added to the early incubation pond before the fry are transferred to avoid stress reactions caused by environmental changes. After the fish fry are transferred indoors, they are first poured into small baskets with a slight flow of water for disinfection. The disinfectant is prepared by mixing formalin solution, copper sulfate and fresh water. After disinfection, the fish fry are evenly distributed into the indoor nursery ponds, the inlet and outlet valves are opened to maintain a continuous slight flow of water, and the oxygen supply is increased appropriately. S5. Cultivate, strengthen, and disinfect the biological baits Daphnia mongolica, Artemia, and copepods; S6. Indoor phased feeding and feed transfer: After the fry are transferred to the indoor nursery pond, they are initially fed with Daphnia mongolica, copepods and newly hatched Artemia; when 60% of the fry have a mouth gape greater than 3.5 mm, they are fed with Daphnia mongolica and Artemia medium; when 60% of the fry have a mouth gape greater than 5 mm, feed acclimatization is started, during which a combination of live feed and artificial feed is used. The live feed includes Daphnia mongolica and adult Artemia. S7. During indoor fry rearing, control the fry density to 3000-4000 fry / meter. 3 And conduct daily management.

2. The method for large-scale grouper breeding based on outdoor-indoor relay cultivation according to claim 1, characterized in that: In step S5, the cultivation and treatment of Artemia includes: pre-stocking dormant Artemia eggs indoors and refrigerating them; using 1 ton of water for incubation and cultivation, incubating at a ratio of 1 ton of water to 1.5 kg of dormant Artemia eggs; controlling the water temperature above 26℃, filtering and collecting Artemia after 20-30 hours of incubation, rinsing the Artemia with fresh water until there are no excess eggshells; temporarily storing the Artemia in the prepared water, strengthening disinfection, and then using it for later use. The expansion and processing of Daphnia mongholica includes: expanding Daphnia mongholica two weeks in advance, collecting Daphnia mongholica after expansion, washing to remove impurities, and then strengthening it for later use. The treatment and breeding of copepods include: one week in advance, detoxifying and culturing copepods in flowing water, adding beneficial bacteria, drugs and povidone-iodine daily for disinfection and sterilization, and feeding them after one week of disinfection and sterilization and passing the test.

3. The method for large-scale grouper breeding based on outdoor-indoor relay cultivation according to claim 1, characterized in that: In step S6, the initial feeding ratio is as follows: the feeding amount of Daphnia mongolica, newly hatched Artemia, and copepods is 180-220g, 90-110g, and 90-110g respectively for 10,000 fish fry; during the feeding process, the amount of Daphnia mongolica and newly hatched Artemia increases by 5% every day, while the amount of copepods remains unchanged. When the mouth gape of the fish fry is greater than 3.5 mm, the feeding amount of Daphnia mongholicus and Artemia tataricus is 280~320g and 190~210g respectively for 10,000 fish fry. When the mouth cleft of the fish fry is greater than 5mm, the initial feeding amount of Daphnia mongholicus and adult Artemia is 300-400g and 100-150g respectively for 10,000 fish fry; the amount of live feed is reduced by 15% every day. The initial feeding amount of artificial feed is 20g per 10,000 fish fry, and then the amount is increased by 30g per 10,000 fish fry per day thereafter.

4. The method for large-scale grouper breeding based on outdoor-indoor relay cultivation according to claim 3, characterized in that: In step S6, the initial feeding ratio is as follows: the feeding amount for Daphnia mongolica, newly hatched Artemia and copepods is 200g, 100g and 100g respectively for 10,000 fish fry. When the mouth gape of the fish fry is greater than 3.5 mm, the feeding amount of Daphnia mongholicus and Artemia tataricus is 300g and 200g respectively for 10,000 fish fry. When the mouth cleft of the fish fry is greater than 5mm, the initial feeding amount of Daphnia mongholicus and adult Artemia is 350g and 130g respectively for 10,000 fish fry.

5. The method for large-scale grouper breeding based on outdoor-indoor relay cultivation according to claim 1, characterized in that: In step S7, on the day the fish fry are introduced into the indoor nursery pond, a small amount of feed is given; the water in the nursery pond is changed every evening for 12 hours, and the amount of water changed is 28-32% of the total water volume in the nursery pond; anti-stress drugs are added to the pond half an hour before the water change; and bottom suction is performed once every 7 days.

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