Ecological breeding method for grouper in low-position pond

Abstract

The invention provides an ecological grouper breeding method in a low-position pond, and relates to the technical field of grouper breeding, the method comprises the following steps: S1, arranging the bottom of the low-position pond and disinfecting the pond; s2, planting probiotics at the pond bottom and the pond wall of the pond; s3, constructing a water ecological environment in the pond; s4, grouper breeding. According to the method, a bionic ecological system closer to the actual survival environment of groupers is constructed, the water quality of the pond can be improved by utilizing probiotics in the breeding process, a suitable survival environment is provided for the growth of fries, meanwhile, interference of an outdoor environment is reduced as much as possible, the survival rate and the production efficiency of breeding are improved, and the breeding cost is reduced. The grouper fry breeding cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of grouper breeding, and in particular to an ecological seedling breeding method for grouper in a low-position pond. Background Art

[0002] Grouper is a carnivorous reef-dwelling fish that lives in tropical and subtropical waters. It belongs to the family Epinephelus of the order Perciformes. The family includes 16 genera and 165 species with rich and diverse phenotypes. Grouper is known for its delicious meat and rich nutrition. It is known as the "chicken of the sea" and is an important edible fish in my country's southern coastal areas. Guangdong Province, Hainan Province and Fujian Province are important suppliers of grouper seedlings and commercial fish farming areas in my country. According to my country's Fisheries Statistical Yearbook, the annual output of grouper has reached 241,000 tons, ranking fourth in my country's marine fish production, and is an important farmed economic fish in my country.

[0003] The seedling stage is an important process in the grouper industry. Improving the survival rate in the seedling stage is an important measure to ensure the healthy operation of the grouper industry. Seedling cultivation refers to the process from the fertilized eggs of grouper to the metamorphosis of young fish, and it is also the process with a high mortality rate in the grouper breeding process. At present, grouper seedlings are mainly carried out in outdoor ponds or indoor pools. The indoor environment is controllable, but the infrastructure costs are huge, the energy consumption is large, and the fault tolerance rate is low. Although the environment of outdoor ponds is relatively uncontrollable, the pond area is large, the buffer is strong, it is closer to the natural state, the energy consumption is low, and the infrastructure is simple. It is still sought after by the majority of users. Ponds are divided into high-level ponds and low-level ponds according to the relative position of the pond bottom to the horizontal plane. The pond bottom is above the horizontal plane, which is a high-level pond, and the pond bottom is below the horizontal plane, which is a low-level pond. High-level ponds and low-level ponds have completely different characteristics. The bottom of high-level ponds can be drained, the water level can be lower than that of low-level ponds, the pond can be dried out, and film can be laid, so it is easier to clean. Low-level ponds require a water pump to pump out the water below the horizontal surface. The drying effect is not good, and film cannot be laid. It is very difficult to clean completely. Therefore, the two also have different methods during use.

[0004] In view of this, it is necessary to design an improved ecological seedling raising method for grouper in low-position ponds to solve the above problems. Summary of the invention

[0005] The invention aims to provide a method for ecological breeding of grouper in a low-position pond.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for ecological breeding of grouper in a low-position pond, comprising the following steps: S1. Layout of low-level pond bottom and pond disinfection: The layout of the bottom of the low-level pond is carried out as follows: first, a layer of fine sand with a thickness of 8-12 cm and a particle size of 0.25-0.35 mm is laid on the bottom of the low-level pond with an area of ​​2-4 mu, and a layer of coral stone with a thickness of 8-12 cm is laid within 2m from the edge of the pond wall, and then the pond is cleaned; S2. Planting probiotics on the bottom and walls of the pond: Choose a time when the tide is high to add water, and use a 200-mesh silk mesh bag to filter the water at the water inlet. When the seawater is 10-20 cm above the highest point of the pond bottom, stop adding water. Inject no less than 1×10 6 cfu / m 3 Bacillus subtilis, 2×10 6 cfu / m 3 nitrifying bacteria, 1×10 6 cfu / m 3 Denitrifying bacteria, 2×10 6 cfu / m 3 photosynthetic bacteria, 10ppm fish paste, 3ppm urea, 20ppm sucrose or glucose, culture for 72-96h to allow the probiotics to attach to the gravel, coral stones and pond walls. After the culture is completed, the seawater in the pond is completely drained; S3. Constructing water ecological environment in ponds: Choose a time period with high tide to refill the pond, and use a 200-mesh silk bag to filter the water at the water inlet. When the water level reaches 1.5-3m, stop filling the pond and let it stand. When the water transparency reaches more than 80cm, disinfect the water. After disinfection, set up several air aeration plates in the pond, and the aeration rate of each aeration plate should not be less than 20L / min. Then add 0.2ppm urea, 0.05ppm dipotassium hydrogen phosphate, 2ppm glucose, and 0.1ppm fish slurry fully fermented by lactic acid bacteria to the water. Each cubic meter of water should be injected with no less than 1×10 5 cfu / m 3 Bacillus subtilis, not less than 1×10 5 cfu / m 3 Denitrifying bacteria, not less than 2×10 5 cfu / m 3 Photosynthetic bacteria, not less than 1×10 5 cfu / m 3 of Chlorella, and not less than 1×10 5 cfu / m 3 of Nannochloropsis ; When the water quality turns light green, within 5-12 days before seedling raising, inoculate the pond with ultramicroscopic rotifers with a long diameter of no more than 140μm and a short diameter of no more than 100μm. The inoculation is divided into 3 times, and the inoculation amount is 1-2 billion rotifers with good vitality each time. Inoculate once every 24 hours. After the last inoculation, check the number of rotifers in the pond 24 hours after the last inoculation. When the number of rotifers per liter of seawater is greater than 100, prepare for seedling raising. During the seedling raising process, the water temperature cannot be lower than 22℃; S4. Breeding of grouper: Place the sterilized fertilized eggs in a hatching bag, fill the hatching bucket with clean seawater and add povidone iodine with a final concentration of 5 ppm of effective iodine, then place the hatching bag in the hatching bucket and let it stand for 15 minutes under aeration; fry will start to eat external food 48-72 hours after hatching, and prepare to open the hatching bag before dawn; 12 hours before opening the hatching bag, sprinkle no less than 1×10 5 cfu / m 3 Yeast, not less than 1×10 6 cfu / m 3 of lactic acid bacteria, not less than 1×10 5 cfu / m 3 of flat algae and no less than 1ppm of glucose to strengthen the rotifers in the pond; 1 hour before opening the hatching bag, inject 0.5ppm vitamin C, 0.1ppm vitamin E, 0.5ppm astragalus polysaccharide, and 1ppm glucose into the hatching bag, and inject 0.1ppm vitamin C, 0.02ppm vitamin E, and 1ppm glucose into the pond outside the hatching bag; then, open the hatching bag and let the fry slowly swim into the pond; 12 days before opening the bag, inject 0.02-0.04ppm urea, 0.5ppm glucose, and 0.005-0.01ppm potassium dihydrogen phosphate every day to maintain the algae phase, and keep the water transparency between 30-90cm; Starting from the 7th day after opening, 0.1-0.5ppm solid chlorine dioxide particles, 0.1-0.3ppm astragalus polysaccharide, 0.5-1ppm glucose, 0.005-0.01ppm vitamin C, 0.005-0.01ppm taurine, and 1ppm polybasic organic acid were added to the pond every day and evenly sprinkled throughout the pond. In addition, no less than 1×10 5 cfu / m 3 photosynthetic bacteria; After 7 days of hatching, start feeding artificially hatched brine shrimp larvae. The initial feeding amount is 1000g of brine shrimp larvae hatched from dormant eggs. After 2 hours of feeding, use a 100-mesh dredger to enrich seawater at the feeding site. If the number of brine shrimp larvae remaining in 100L of seawater is less than 20, it is considered to have eaten. Double the feeding the next day until the number of brine shrimp larvae remaining in 100L of seawater is greater than 20. Maintain the feeding amount. When the feeding amount is insufficient again, increase the feeding amount by 20% every day thereafter until the fry are 20 days old. Starting from the 20th day after the fish start to fish, start feeding sword Daphnia with a long diameter of 0.5-2mm, mixed with brine shrimp larvae, and increase the amount of sword Daphnia by 20% every day until the sword Daphnia completely replaces the brine shrimp larvae. After the bait conversion is completed, continue to feed sword Daphnia until the fry complete the metamorphosis and become juveniles. In the later stage of seedling rearing, check whether the bait is sufficient by salvaging every day, and increase the feeding amount of the next day according to the remaining amount of biological bait until the fry complete the metamorphosis.

[0007] Preferably, in step S4, the sword Daphnia needs to be strengthened before being released, and the strengthening method is as follows: after the hatching bucket is filled with seawater, no less than 1×10 5 cfu / m 3 of lactic acid bacteria, not less than 1×10 5 cfu / m 3 brewer's yeast, 10ppm fish oil, 10ppm shrimp meal, 1ppm Schizochytrium, 0.5ppm vitamin C, 0.02ppm vitamin E, 0.01ppm vitamin A and 0.01ppm folic acid, and aerate vigorously, put the insect bodies into the hatching bucket, the dead insect bodies will rise to the surface with the bubbles to form foam, remove the foam every 10-20 minutes, and the strengthening time is 2-5h.

[0008] Preferably, in step S4, before placing the fertilized eggs into the hatching bags, 500 ppm of photosynthetic bacteria, 5 ppm of polybasic organic acid, 5 ppm of disodium ethylenediaminetetraacetate, and 5 ppm of 100-mesh activated carbon powder are added to each hatching bag.

[0009] Preferably, in step S3, the disinfection method is as follows: use a water truck to mix the bleaching powder in the pond, and after the water body is disinfected for 48 hours, use 0.2-0.6ppm copper acetate to disinfect the water environment. After copper acetate disinfection for 48 hours, use 3-5ppm polybasic organic acid and 0.5-1ppm disodium ethylenediaminetetraacetic acid to detoxify the water body for 48 hours.

[0010] Preferably, in step S1, pond disinfection is carried out according to the following steps: seal the pond drain, place the high-pressure water gun water inlet into a bucket containing bleach, and use a water gun with a pressure of 0.3-0.5 bar to oxidize and disinfect the pond bottom and pond wall; after the disinfection is completed, use a water gun with a pressure of 0.3-0.5 bar to draw clean seawater to clean the entire pond.

[0011] Preferably, in step S1, the pond cleaning operation is performed as follows: use a high-pressure water gun with a pressure of not less than 2 bar to clean the pond, and use the high-pressure water gun to gradually turn over the sand from the center of the pond to the pond wall until the sand shows its original color and no organic matter and other impurities are attached to the surface of the coral stone; after cleaning, use a water gun with a pressure of 0.3-0.5 bar to rinse the sand bottom and coral stone flat.

[0012] Preferably, in step S1, the bleaching liquid is prepared as follows: 800 L of seawater is placed in a 1-ton wide-mouthed bucket, bleaching powder is filtered through a 40-mesh screen, the bleaching powder is gradually dissolved in the bucket, stirred sufficiently, and the insoluble residue in the filter screen is discarded to obtain the bleaching liquid.

[0013] Preferably, in step S1, the dosage of bleaching powder is 20 kg per mu; the disinfection time is in the evening when the light is weak.

[0014] Preferably, in step S4, the method for placing photosynthetic bacteria is as follows: the photosynthetic bacteria are placed in a 1-ton incubation bucket, a hose with a diameter of 6-8 mm and a lead weight is connected to the bottom of the incubation bucket and hung down to the bottom of the pond, the photosynthetic bacteria are driven into the bottom of the pond, and the photosynthetic bacteria are slowly covered with the water flow until the metamorphosis is completed on the 30th day.

[0015] Preferably, in step S3, the usage amount of the bleaching powder is 10-15 ppm.

[0016] The beneficial effects of the present invention are: The present invention provides an ecological seedling raising method for grouper in a low-position pond. The method selects a low-position pond as a seedling raising site and artificially colonizes a specific type of probiotics therein, thereby constructing an artificial ecosystem that is closer to the actual living environment of grouper. Grouper seedlings are raised in this environment, and the probiotics therein can be used to improve the pond water quality during the seedling raising process, thereby providing a suitable living environment for the growth of the seedlings. At the same time, the interference of the outdoor environment is reduced as much as possible, the survival rate and production efficiency of the seedlings are improved, and the cost of grouper seedling raising is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention provides a schematic flow chart of the method for ecological breeding of grouper in a low-position pond. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0020] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0021] See also Figure 1 As shown, the method for ecological breeding of grouper in low-position ponds provided by the present invention comprises the following steps: S1. Layout of low-level pond bottom and pond disinfection: The bottom layout of the low-level pond is carried out as follows: 8-12cm thick fine sand with a particle size of 0.25-0.35mm is laid on the bottom of the low-level pond with an area of ​​2-4 mu, and 8-12cm thick coral stones are laid within 2m from the edge of the pond wall to attach probiotics and maintain ventilation, and then the pond is cleaned; The pond disinfection is carried out in the following steps: block the pond drain, place the high-pressure water gun water inlet into a bucket of bleach, and use a water gun with a pressure of 0.3-0.5 bar to oxidize and disinfect the bottom and wall of the pond. If the bleach is not enough, place the high-pressure water gun source outlet in the low-lying area of ​​the pond, extract the collected bleach after cleaning, and clean it again until the sand and coral stones show their original color, and then use a water gun with a pressure of 0.3-0.5 bar to extract clean seawater to clean the entire pond; S2. Planting probiotics on the bottom and walls of the pond: Choose a time when the tide is high to add water, and use a 200-mesh silk mesh bag to filter the water at the water inlet. When the seawater is 10-20 cm above the highest point of the pond bottom, stop adding water. Inject no less than 1×10 6 cfu / m 3 Bacillus subtilis, 2×10 6 cfu / m 3 nitrifying bacteria, 1×10 6 cfu / m 3 Denitrifying bacteria, 2×10 6 cfu / m 3photosynthetic bacteria, 10ppm fish slurry, 3ppm urea, 20ppm sucrose or glucose, install a 1000-watt four-wheeled waterwheel 2m away from the pond wall at two diagonal angles of the pond, turn on the waterwheel to keep the water moving; culture under the above conditions for 72-96 hours to facilitate the attachment of probiotics to gravel, coral stones and pond walls, and completely drain the seawater in the pond after the culture is completed; S3. Constructing water ecological environment in ponds: Choose a time period with high tide to refill the pond, and use a 200-mesh silk bag to filter the water at the water inlet. When the water level reaches 1.5-3m, stop filling the pond and let it stand. When the water transparency reaches more than 80cm, disinfect the water. After disinfection, set an air aeration plate at each of the four corners and the center of the pond. The aeration rate of each aeration plate should not be less than 20L / min. Then add 0.2ppm urea, 0.05ppm dipotassium hydrogen phosphate, 2ppm glucose, and 0.1ppm fish slurry fully fermented by lactic acid bacteria to the water. Each cubic meter of water should be injected with no less than 1×10 5 cfu / m 3 Bacillus subtilis, not less than 1×10 5 cfu / m 3 Denitrifying bacteria, not less than 2×10 5 cfu / m 3 Photosynthetic bacteria, not less than 1×10 5 cfu / m 3 of Chlorella, and not less than 1×10 5 cfu / m 3 Keep the waterwheel turning until the water turns a bright green color; When the water quality turns light green, within 5-12 days before seedling raising, inoculate the pond with ultramicroscopic rotifers with a long diameter of no more than 140μm and a short diameter of no more than 100μm. The inoculation is divided into 3 times, and the inoculation amount each time is 1-2 billion rotifers with good vitality. Inoculate once every 24 hours. 24 hours after the last inoculation, check the number of rotifers in the pond. If the number of rotifers per liter of seawater is greater than 100, it can be prepared for seedling raising. During the seedling raising process, the water temperature cannot be lower than 22℃; S4. Breeding of grouper: Place the sterilized fertilized eggs in a hatching bag, fill the hatching bucket with clean seawater and add povidone iodine with a final concentration of 5ppm effective iodine, then place the hatching bag in the hatching bucket and let it stand for 15 minutes under aeration; then, use two sets of 200W electromagnetic blower equipment to connect aeration stones for aeration, one for use and one for backup, to ensure that the hatching bag is constantly aerated. When the fry begin to emerge from the membrane, adjust the aeration in the hatching bag to a low level so that no obvious air column is formed; about 48-72 hours after emergence from the membrane, they begin to ingest external food, which can be judged by the presence of three black dots on the eyes and dorsal abdomen, and when the fry are picked up with a beaker, the fry sink to the bottom of the cup and keep pecking at the bottom of the cup. When pecking at the bottom of the cup is found, open the hatching bag before dawn; 12 hours before opening the hatching bag, sprinkle no less than 1×10 5 cfu / m 3 Yeast, not less than 1×10 6 cfu / m 3 of lactic acid bacteria, not less than 1×10 5 cfu / m 3 of flat algae, and glucose not less than 1ppm to strengthen the rotifers in the pond; 1 hour before opening the hatching bag, turn off the waterwheel, inject 0.5ppm vitamin C, 0.1ppm vitamin E, 0.5ppm astragalus polysaccharide, and 1ppm glucose into the hatching bag, and inject 0.1ppm vitamin C, 0.02ppm vitamin E, and 1ppm glucose into the pond outside the hatching bag to prevent the fry from stress. After doing the above work, open the hatching bag and let the fry slowly swim into the pond; 12 days before opening the bag, inject 0.02-0.04ppm urea, 0.5ppm glucose, and 0.005-0.01ppm potassium dihydrogen phosphate every day to maintain the algae phase, and keep the water transparency between 30-90cm; Starting from the 7th day after fry opening, the fry began to metamorphose and grow fin spines. Until the metamorphosis was completed, 0.1-0.5ppm solid chlorine dioxide granules, 0.1-0.3ppm astragalus polysaccharide, 0.5-1ppm glucose, 0.005-0.01ppm vitamin C, 0.005-0.01ppm taurine, and 1ppm polybasic organic acid were added daily and evenly sprinkled throughout the pond. In addition, no less than 1×10 5 cfu / m 3 The photosynthetic bacteria are placed in a 1-ton hatching bucket, and a hose with a diameter of 6-8 mm and a lead weight is connected to the bottom of the hatching bucket, which is hung down to the bottom of the pond. The photosynthetic bacteria are poured into the bottom of the pond and slowly cover the entire pond with the water flow until the metamorphosis is completed on the 30th day. After 7 days of hatching, start feeding artificially hatched brine shrimp larvae. The initial feeding amount is 1000g of brine shrimp larvae hatched from dormant eggs. After 2 hours of feeding, use a 100-mesh dredger to enrich seawater at the feeding site. If the number of brine shrimp larvae remaining in 100L of seawater is less than 20, it is considered to have eaten. Double the feeding the next day until the number of brine shrimp larvae remaining in 100L of seawater is greater than 20. Maintain the feeding amount. When the feeding amount is insufficient again, increase the feeding amount by 20% every day thereafter until the fry are 20 days old. Starting from the 20th day after the fish start to fish, start feeding sword Daphnia with a long diameter of 0.5-2mm, mixed with brine shrimp larvae, and increase the amount of sword Daphnia by 20% every day until the sword Daphnia completely replaces the brine shrimp larvae. After the bait conversion is completed, continue to feed sword Daphnia until the fry complete the metamorphosis and become juveniles. In the later stage of seedling rearing, check whether the bait is sufficient by salvaging every day, and increase the feeding amount of the next day according to the remaining amount of biological bait until the fry complete the metamorphosis.

[0022] In some embodiments, in step S1, the bleaching liquid is prepared as follows: 800L of seawater is placed in a 1-ton wide-mouthed bucket, bleaching powder is filtered through a 40-mesh screen, the bleaching powder is gradually dissolved in the bucket, stirred sufficiently, and the insoluble residue in the filter screen is discarded to obtain the bleaching liquid. The dosage of the bleaching powder is 20kg per mu. In particular, in some embodiments, the pond is disinfected in the evening when the light is weak to ensure the disinfection effect.

[0023] In some embodiments, in step S1, the pond cleaning operation is performed as follows: the pond is cleaned using a high-pressure water gun with a pressure of not less than 2 bar, and the sand is gradually turned up from the center of the pond to the pond wall with the high-pressure water gun until the sand shows its original color and no organic matter and other dirt are attached to the surface of the coral stone. After cleaning, the sand bottom and coral stone are washed and leveled using a water gun with a pressure of 0.3-0.5 bar.

[0024] In some embodiments, in step S3, the disinfection method is as follows: bleaching powder is mixed in the pond by a water truck, and after the water body is disinfected for 48 hours, 0.2-0.6ppm copper acetate is used to disinfect the water environment, and after 48 hours of copper acetate disinfection, 3-5ppm polybasic organic acid and 0.5-1ppm disodium ethylenediaminetetraacetate are used to detoxify the water body for 48 hours. The amount of bleaching powder used is 10-15ppm.

[0025] In some embodiments, in step S4, the sword Daphnia need to be strengthened before being released. The strengthening method is as follows: after the hatching bucket is filled with seawater, no less than 1×10 5 cfu / m 3 of lactic acid bacteria, not less than 1×10 5 cfu / m 3brewer's yeast, 10ppm fish oil, 10ppm shrimp meal, 1ppm Schizochytrium, 0.5ppm vitamin C, 0.02ppm vitamin E, 0.01ppm vitamin A and 0.01ppm folic acid, and aerate vigorously, put the insect bodies into the hatching bucket, the dead insect bodies will rise to the surface with the bubbles to form foam, remove the foam every 10-20 minutes, and the strengthening time is 2-5h.

[0026] In some embodiments, in step S4, before placing the fertilized eggs into the hatching bags, 500 ppm of photosynthetic bacteria, 5 ppm of polybasic organic acid, 5 ppm of disodium ethylenediaminetetraacetate, and 5 ppm of 100-mesh activated carbon powder are added to each hatching bag.

[0027] The method for raising grouper in low-position pond ecological seedlings proposed by the present invention is further described below in conjunction with specific embodiments: Example

[0028] This embodiment provides a method for ecological breeding of grouper in a low-position pond, comprising the following steps: S1. Layout of low-level pond bottom and pond disinfection: The bottom layout of the low-level pond was carried out as follows: first, 12cm thick fine sand with a particle size of 0.3-0.35mm was laid on the bottom of three low-level ponds with an area of ​​3 mu, and 10cm thick coral stones were laid within 2m from the edge of the pond wall to attach probiotics and maintain air permeability; after laying, the pond was cleaned; The pond disinfection is carried out in the following steps: block the pond drain, place the high-pressure water gun water inlet into a bucket of bleach, and use a water gun with a pressure of 0.5 bar to oxidize and disinfect the bottom and wall of the pond. If the bleach is not enough, place the high-pressure water gun source outlet in the low-lying area of ​​the pond, extract the collected bleach after cleaning, and clean it again until the sand and coral stones show their original color, and then use a water gun with a pressure of 0.5 bar to extract clean seawater to clean the entire pond; The preparation method of the bleaching liquid is as follows: 800L of seawater is placed in a 1-ton wide-mouthed bucket, bleaching powder is filtered through a 40-mesh screen, the bleaching powder is gradually dissolved in the bucket, stirred sufficiently, and the insoluble residue in the filter screen is discarded to obtain the bleaching liquid, and the dosage of the bleaching powder is 20kg per mu; in particular, to ensure the disinfection effect, the pond is disinfected in the evening when the light is weak; The pond cleaning operation is carried out as follows: use a high-pressure water gun with a pressure of 2 bar to clean the pond, and use the high-pressure water gun to gradually turn over the sand from the center of the pond to the pond wall until the sand shows its original color and the surface of the coral stone is free of organic matter and other dirt; after cleaning, use a water gun with a pressure of 0.5 bar to wash and level the sand bottom and coral stone; S2. Planting probiotics on the bottom and walls of the pond: Choose a time when the tide is high to add water, and use a 200-mesh silk mesh bag to filter the water at the water inlet. When the seawater is 20 cm above the highest point of the pond bottom, stop adding water. Put 1×10 6 cfu / m 3 Bacillus subtilis, 2×10 6 cfu / m 3 nitrifying bacteria, 1×10 6 cfu / m 3 Denitrifying bacteria, 2×10 6 cfu / m 3 photosynthetic bacteria, 10ppm fish slurry, 3ppm urea, 20ppm sucrose or glucose, and install a 1000-watt four-wheeled waterwheel 2m away from the pond wall at two diagonal angles of the pond. Turn on the waterwheel to keep the water moving; culture for 96 hours under the above conditions to facilitate the attachment of probiotics to gravel, coral stones and pond walls. After the culture is completed, the seawater in the pond is completely drained; S3. Constructing water ecological environment in ponds: Choose a time period with high tide to refill the pond, and use a 200-mesh silk bag to filter the water at the water inlet. When the water level reaches 2.8m, stop filling the pond and let it stand. When the water transparency reaches 80cm, disinfect the water. After disinfection, set an air aeration plate at each of the four corners and the center of the pond. The aeration rate of each aeration plate should not be less than 20L / min. Then add 0.2ppm urea, 0.05ppm dipotassium hydrogen phosphate, 2ppm glucose, and 0.1ppm fish slurry fully fermented by lactic acid bacteria to the water. Add 1×10 5 cfu / m 3 Bacillus subtilis, 1×10 5 cfu / m 3 Denitrifying bacteria, 2×10 5 cfu / m 3 Photosynthetic bacteria, 1×10 5 cfu / m 3 of Chlorella, and not less than 1×10 5 cfu / m 3 Keep the waterwheel turning until the water turns a bright green color; The disinfection method is as follows: use a water truck to mix bleach in the pond, disinfect the water body for 48 hours, then use 0.2ppm copper acetate to disinfect the water environment, and after 48 hours of copper acetate disinfection, use 3ppm polybasic organic acid and 0.5ppm disodium ethylenediaminetetraacetic acid to detoxify the water body for 48 hours, and the amount of bleach used is 10ppm; When the water quality turns light green, within 5 days before seedling raising, inoculate the pond with ultramicroscopic rotifers with a long diameter of no more than 140μm and a short diameter of no more than 100μm. The inoculation is divided into 3 times, and the inoculation amount is 1 billion rotifers with good vitality each time. Inoculate once every 24 hours. After the last inoculation, check the number of rotifers in the pond 24 hours after the last inoculation. If the number of rotifers per liter of seawater is greater than 100, it is ready for seedling raising. During the seedling raising process, the water temperature is 27-29℃; S4. Breeding of grouper: The sterilized fertilized eggs were placed in a waterproof hatching bag made of water canvas with a volume of 12 cubic meters. The hatching bucket was filled with clean seawater and povidone iodine with a final concentration of 5 ppm of effective iodine was added. The hatching bag was then placed in the hatching bucket and allowed to stand for 15 minutes under aeration. Then, two sets of 200W electromagnetic blower equipment were connected to aeration stones for aeration, one for use and one for backup, to ensure that the hatching bag was constantly aerated. When the fry began to emerge from the membrane, the aeration in the hatching bag was adjusted to a low level so that no obvious air column would be formed. After 56 hours of emergence from the membrane, the fry began to ingest external food. The judgment method was that three black dots grew on the eyes and dorsal abdomen, and when the fry were picked up with a beaker, the fry sank to the bottom of the cup and kept pecking at the bottom of the cup. When the pecking at the bottom of the cup was found, the hatching bag was opened before dawn. 12 hours before opening the hatching bag, 1×10 5 cfu / m 3 Yeast, 1×10 6 cfu / m 3 Lactobacillus, 1×10 5 cfu / m 3 1ppm of flat algae and 1ppm of glucose to strengthen the rotifers in the pond; 1 hour before opening the hatching bag, turn off the water wheel, inject 0.5ppm vitamin C, 0.1ppm vitamin E, 0.5ppm astragalus polysaccharide and 1ppm glucose into the hatching bag, and inject 0.1ppm vitamin C, 0.02ppm vitamin E and 1ppm glucose into the pond outside the hatching bag to prevent the fry from stress. After doing the above work, open the hatching bag and let the fry slowly swim into the pond; 12 days before opening the bag, inject 0.02ppm urea, 0.5ppm glucose and 0.005ppm potassium dihydrogen phosphate every day to maintain the algae phase and keep the water transparency at 60cm; Starting from the 7th day after fry opening, the fry began to metamorphose and grow fin spines. Until the metamorphosis was completed, 0.1ppm solid chlorine dioxide granules, 0.1ppm astragalus polysaccharide, 0.5ppm glucose, 0.005ppm vitamin C, 0.005ppm taurine, and 1ppm polybasic organic acid were added daily and evenly sprinkled throughout the pond. In addition, no less than 1×10 5 cfu / m 3The photosynthetic bacteria are placed in a 1-ton hatching bucket, and a 6mm diameter hose with a lead weight is connected to the bottom of the hatching bucket, which is hung all the way to the bottom of the pond. The photosynthetic bacteria are poured into the bottom of the pond and slowly cover the entire pond with the water flow until the metamorphosis is completed on the 30th day. After 7 days of hatching, start feeding artificially hatched brine shrimp larvae. The initial feeding amount is 1000g of brine shrimp larvae hatched from dormant eggs. After 2 hours of feeding, use a 100-mesh dredger to enrich seawater at the feeding site. If the number of brine shrimp larvae remaining in 100L of seawater is less than 20, it is considered to have eaten. Double the feeding the next day until the number of brine shrimp larvae remaining in 100L of seawater is greater than 20. Maintain the feeding amount. When the feeding amount is insufficient again, increase the feeding amount by 20% every day thereafter until the fry are 20 days old. From the 20th day after the fish start to hatch, they start to feed 0.5-2mm long diameter sword daphnia and mix them with brine shrimp larvae. Increase the sword daphnia by 20% every day until the sword daphnia completely replace the brine shrimp larvae. After the feed conversion is completed, continue to feed sword daphnia until the fry metamorphosis is completed and become juveniles. Sword daphnia need to be strengthened before they are released. The strengthening method is as follows: after filling the hatching bucket with seawater, inject 1×10 5 cfu / m 3 Lactobacillus, 1×10 5 cfu / m 3 of brewer's yeast, 10ppm fish oil, 10ppm shrimp meal, 1ppm Schizochytrium, 0.5ppm vitamin C, 0.02ppm vitamin E, 0.01ppm vitamin A and 0.01ppm folic acid, and aerate vigorously, put the worms into the hatching bucket, the dead worms will rise to the surface with the bubbles to form foam, and the foam will be removed every 20 minutes, and the strengthening time is 5h; in the late stage of seedling rearing, check whether the bait is sufficient by salvaging every day, and increase the feeding amount of the next day according to the remaining amount of biological bait until the fry completes metamorphosis. In particular, before putting the fertilized eggs into the hatching bag, 500ppm photosynthetic bacteria, 5ppm polyorganic organic acid, 5ppm disodium ethylenediaminetetraacetic acid, 5ppm100 mesh activated carbon powder should be added to each hatching bag, and 0.6kg of tiger dragon hybrid spot eggs should be placed in each pond.

[0029] The traditional low-level pond seedling raising method is carried out in the following steps: select 3 low-level ponds with an area of ​​3.6 mu for seedling raising, directly introduce seawater into the low-level ponds, wait for the seawater to turn from red to green, add 5 kg of fish meal, 5 kg of molasses, and 10×10 6 cfu / m 3Bacillus, wait for the protozoa in the pond to multiply, about 5 days later, set up a cloth basket, and put 0.6kg of tiger dragon hybrid eggs in each pond; 56 hours after the fish eggs are put in, the fish are put into the outer pond to feed on the original pond protozoa and biological bait, and after about 20 days, start to put cladocerans or copepods cultured with chicken manure into the pond until the metamorphosis of the fry is completed. Among them, the temperature of the frying process is 27-29℃.

[0030] After the cultivation is completed, the results of the ecological seedling raising method of this embodiment and the traditional low-position pond seedling raising method are respectively counted, and the results are shown in Table 1. The results show that the average survival rate of seedlings raised by the ecological seedling raising method can reach 50.27%, while the average survival rate of the traditional seedling raising method is only 7.88%, indicating that the seedling raising method proposed by the present invention can significantly improve the survival rate of fry. Among them, the calculation formula of the seedling raising survival rate is: seedling raising survival rate = number of hatched fish flowers / number of young fish that have completed metamorphosis × 100%.

[0031] Table 1 Seedling raising results of ecological seedling raising method and traditional low-position pond seedling raising method Example

[0032] This embodiment provides a method for ecological breeding of grouper in a low-position pond, comprising the following steps: S1. Layout of low-level pond bottom and pond disinfection: The bottom layout of the low-level pond was carried out as follows: first, 12cm thick fine sand with a particle size of 0.3-0.35mm was laid on the bottom of three low-level ponds with an area of ​​2.6 mu, and 10cm thick coral stones were laid within 2m from the edge of the pond wall to attach probiotics and maintain air permeability; after laying, the pond was cleaned; The pond disinfection is carried out in the following steps: block the pond drain, place the high-pressure water gun water inlet into a bucket of bleach, and use a water gun with a pressure of 0.5 bar to oxidize and disinfect the bottom and wall of the pond. If the bleach is not enough, place the high-pressure water gun source outlet in the low-lying area of ​​the pond, extract the collected bleach after cleaning, and clean it again until the sand and coral stones show their original color, and then use a water gun with a pressure of 0.5 bar to extract clean seawater to clean the entire pond; The preparation method of the bleaching liquid is as follows: 800L of seawater is placed in a 1-ton wide-mouthed bucket, bleaching powder is filtered through a 40-mesh screen, the bleaching powder is gradually dissolved in the bucket, stirred sufficiently, and the insoluble residue in the filter screen is discarded to obtain the bleaching liquid, and the dosage of the bleaching powder is 20kg per mu; in particular, to ensure the disinfection effect, the pond is disinfected in the evening when the light is weak; The pond cleaning operation is carried out as follows: use a high-pressure water gun with a pressure of 2 bar to clean the pond, and use the high-pressure water gun to gradually turn over the sand from the center of the pond to the pond wall until the sand shows its original color and the surface of the coral stone is free of organic matter and other dirt; after cleaning, use a water gun with a pressure of 0.5 bar to wash and level the sand bottom and coral stone; S2. Planting probiotics on the bottom and walls of the pond: Choose a high tide time to add water, and use a 200-mesh silk mesh bag to filter the water at the water inlet. When the seawater is 15 cm above the highest point of the pond bottom, stop adding water. Inject no less than 1×10 6 cfu / m 3 Bacillus subtilis, 2×10 6 cfu / m 3 nitrifying bacteria, 1×10 6 cfu / m 3 Denitrifying bacteria, 2×10 6 cfu / m 3 photosynthetic bacteria, 10ppm fish slurry, 3ppm urea, 20ppm sucrose or glucose, and install a 1000-watt four-wheeled waterwheel 2m away from the pond wall at two diagonal angles of the pond. Turn on the waterwheel to keep the water moving; culture for 80 hours under the above conditions to facilitate the attachment of probiotics to gravel, coral stones and pond walls. After the culture is completed, the seawater in the pond is completely drained; S3. Constructing water ecological environment in ponds: Choose a time period with high tide to refill the pond, and use a 200-mesh silk bag to filter the water at the water inlet. When the water level reaches 2.8m, stop filling the pond and let it stand. When the water transparency reaches 80cm, disinfect the water. After disinfection, set an air aeration plate at each of the four corners and the center of the pond. The aeration rate of each aeration plate should not be less than 20L / min. Then add 0.2ppm urea, 0.05ppm dipotassium hydrogen phosphate, 2ppm glucose, and 0.1ppm fish slurry fully fermented by lactic acid bacteria to the water. Add 1×10 5 cfu / m 3 Bacillus subtilis, 1×10 5 cfu / m 3 Denitrifying bacteria, 2×10 5 cfu / m 3 Photosynthetic bacteria, 1×10 5 cfu / m 3 Chlorella, 1×10 5 cfu / m 3 Keep the waterwheel turning until the water turns a bright green color; The disinfection method is as follows: use a water truck to mix bleach in the pond, disinfect the water body for 48 hours, then use 0.2ppm copper acetate to disinfect the water environment, and after 48 hours of copper acetate disinfection, use 3ppm polybasic organic acid and 0.5ppm disodium ethylenediaminetetraacetic acid to detoxify the water body for 48 hours, and the amount of bleach used is 10ppm; When the water quality turns light green, within 5 days before seedling raising, inoculate the pond with ultramicroscopic rotifers with a long diameter of no more than 140μm and a short diameter of no more than 100μm. The inoculation is divided into 3 times, and the inoculation amount is 1 billion rotifers with good vitality each time. Inoculate once every 24 hours. After the last inoculation, check the number of rotifers in the pond 24 hours after the last inoculation. If the number of rotifers per liter of seawater is greater than 100, it is ready for seedling raising. During the seedling raising process, the water temperature is 29-32℃; S4. Breeding of grouper: The sterilized fertilized eggs were placed in a waterproof hatching bag made of water canvas with a volume of 12 cubic meters. The hatching bucket was filled with clean seawater and povidone iodine with a final concentration of 5 ppm of effective iodine was added. The hatching bag was then placed in the hatching bucket and allowed to stand for 15 minutes under aeration. Then, two sets of 200W electromagnetic blower equipment were connected to aeration stones for aeration, one for use and one for backup, to ensure that the hatching bag was constantly aerated. When the fry began to emerge from the membrane, the aeration in the hatching bag was adjusted to a low level so that no obvious air column would be formed. After 56 hours of emergence from the membrane, the fry began to ingest external food. The judgment method was that three black dots grew on the eyes and dorsal abdomen, and when the fry were picked up with a beaker, the fry sank to the bottom of the cup and kept pecking at the bottom of the cup. When the pecking at the bottom of the cup was found, the hatching bag was opened before dawn. 12 hours before opening the hatching bag, 1×10 5 cfu / m 3 Yeast, 1×10 6 cfu / m 3 Lactobacillus, 1×10 5 cfu / m 3 1ppm of flat algae and 1ppm of glucose to strengthen the rotifers in the pond; 1 hour before opening the hatching bag, turn off the water wheel, inject 0.5ppm vitamin C, 0.1ppm vitamin E, 0.5ppm astragalus polysaccharide and 1ppm glucose into the hatching bag, and inject 0.1ppm vitamin C, 0.02ppm vitamin E and 1ppm glucose into the pond outside the hatching bag to prevent the fry from stress. After doing the above work, open the hatching bag and let the fry slowly swim into the pond; 12 days before opening the bag, inject 0.02ppm urea, 0.5ppm glucose and 0.005ppm potassium dihydrogen phosphate every day to maintain the algae phase and keep the water transparency at 60cm; Starting from the 7th day after fry opening, the fry began to metamorphose and grow fin spines. Until the metamorphosis was completed, 0.1ppm solid chlorine dioxide granules, 0.1ppm astragalus polysaccharide, 0.5ppm glucose, 0.005ppm vitamin C, 0.005ppm taurine, and 1ppm polybasic organic acid were added daily and evenly sprinkled throughout the pond. In addition, no less than 1×10 5 cfu / m 3 The photosynthetic bacteria are placed in a 1-ton hatching bucket, and a 6mm diameter hose with a lead weight is connected to the bottom of the hatching bucket, which is hung all the way to the bottom of the pond. The photosynthetic bacteria are poured into the bottom of the pond and slowly cover the entire pond with the water flow until the metamorphosis is completed on the 30th day. After 7 days of hatching, start feeding artificially hatched brine shrimp larvae. The initial feeding amount is 1000g of brine shrimp larvae hatched from dormant eggs. After 2 hours of feeding, use a 100-mesh dredger to enrich seawater at the feeding site. If the number of brine shrimp larvae remaining in 100L of seawater is less than 20, it is considered to have eaten. Double the feeding the next day until the number of brine shrimp larvae remaining in 100L of seawater is greater than 20. Maintain the feeding amount. When the feeding amount is insufficient again, increase the feeding amount by 20% every day thereafter until the fry are 20 days old. From the 20th day after the fish start to hatch, they start to feed 0.5-2mm long diameter sword daphnia and mix them with brine shrimp larvae. Increase the sword daphnia by 20% every day until the sword daphnia completely replace the brine shrimp larvae. After the feed conversion is completed, continue to feed sword daphnia until the fry metamorphosis is completed and become juveniles. Sword daphnia need to be strengthened before they are released. The strengthening method is as follows: after filling the hatching bucket with seawater, inject 1×10 5 cfu / m 3 Lactobacillus, 1×10 5 cfu / m 3 of brewer's yeast, 10ppm fish oil, 10ppm shrimp meal, 1ppm Schizochytrium, 0.5ppm vitamin C, 0.02ppm vitamin E, 0.01ppm vitamin A and 0.01ppm folic acid, and aerate vigorously, put the insects into the hatching bucket, the dead insects will rise to the surface with the bubbles to form foam, and the foam will be removed every 20 minutes, the strengthening time is 5h, and aerate vigorously, the dead insects will rise to the surface with the bubbles to form foam, and the foam will be removed every 20 minutes; put 1×10 5 cfu / m 3 Lactobacillus, 1×10 5 cfu / m 3of brewer's yeast, 10ppm fish oil, 10ppm shrimp meal, 1ppm Schizochytrium, 0.5ppm vitamin C, 0.02ppm vitamin E, 0.01ppm vitamin A and 0.01ppm folic acid, the strengthening time is 5h; in the late stage of seedling rearing, check whether the bait is sufficient by fishing every day, and increase the feeding amount of the next day according to the remaining amount of biological bait until the fry completes metamorphosis. In particular, before putting the fertilized eggs into the hatching bag, 500ppm photosynthetic bacteria, 5ppm polybasic organic acid, 5ppm disodium ethylenediaminetetraacetic acid, 5ppm 100-mesh activated carbon powder should be added to each hatching bag, and 0.6kg of tiger dragon hybrid spot eggs should be placed in each pond.

[0033] The traditional low-level pond seedling raising method is carried out in the following steps: select 3 low-level ponds with an area of ​​2.6 mu for seedling raising, directly introduce seawater into the low-level ponds, wait for the seawater to turn from red to green, add 5 kg of fish meal, 5 kg of molasses, and 10×10 6 cfu / m 3 Bacillus, wait for the protozoa in the pond to multiply, about 5 days later, set up a cloth basket, and put 0.6kg of tiger dragon hybrid eggs in each pond; 52 hours after the fish eggs are put in, the fish are put into the outer pond to feed on the original pond protozoa and biological bait, and after about 20 days, start to put cladocerans or copepods cultured with chicken manure into the pond until the metamorphosis of the fry is completed. Among them, the temperature of the frying process is 29-32℃.

[0034] After the cultivation is completed, the results of the ecological seedling raising method of this embodiment and the traditional low-position pond seedling raising method are respectively counted, and the results are shown in Table 2. The results show that the average survival rate of seedlings raised by the ecological seedling raising method can reach 39.47%, while the average survival rate of the traditional seedling raising method is only 6.77%, indicating that the seedling raising method proposed by the present invention can significantly improve the survival rate of fry. Among them, the calculation formula of the seedling raising survival rate is: seedling raising survival rate = number of hatched fish flowers / number of young fish that have completed metamorphosis × 100%.

[0035] Table 2 Seedling raising results of ecological seedling raising method and traditional low-position pond seedling raising method

[0036] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for ecological seedling cultivation of grouper in a low-position pond, characterized in that: The steps include: S1. Layout of low-level pond bottom and pond disinfection: The layout of the bottom of the low-level pond is carried out as follows: first, a layer of fine sand with a thickness of 8-12 cm and a particle size of 0.25-0.35 mm is laid on the bottom of the low-level pond with an area of ​​2-4 mu, and a layer of coral stone with a thickness of 8-12 cm is laid within 2m from the edge of the pond wall, and then the pond is cleaned; S2. Planting probiotics on the bottom and walls of the pond: Choose a time when the tide is high to add water, and use a 200-mesh silk mesh bag to filter the water at the water inlet. When the seawater is 10-20 cm above the highest point of the pond bottom, stop adding water. Inject no less than 1×10 6 cfu / m 3 Bacillus subtilis, 2×10 6 cfu / m 3 nitrifying bacteria, 1×10 6 cfu / m 3 Denitrifying bacteria, 2×10 6 cfu / m 3 photosynthetic bacteria, 10ppm fish paste, 3ppm urea, 20ppm sucrose or glucose, culture for 72-96h to allow the probiotics to attach to the gravel, coral stones and pond walls. After the culture is completed, the seawater in the pond is completely drained; S3. Constructing water ecological environment in ponds: Choose a time period with high tide to refill the pond, and use a 200-mesh silk bag to filter the water at the water inlet. When the water level reaches 1.5-3m, stop filling the pond and let it stand. When the water transparency reaches more than 80cm, disinfect the water. After disinfection, set up several air aeration plates in the pond, and the aeration rate of each aeration plate should not be less than 20L / min. Then add 0.2ppm urea, 0.05ppm dipotassium hydrogen phosphate, 2ppm glucose, and 0.1ppm fish slurry fully fermented by lactic acid bacteria to the water. Each cubic meter of water should be injected with no less than 1×10 5 cfu / m 3 Bacillus subtilis, not less than 1×10 5 cfu / m 3 Denitrifying bacteria, not less than 2×10 5 cfu / m 3 Photosynthetic bacteria, not less than 1×10 5 cfu / m 3 of Chlorella, and not less than 1×10 5 cfu / m 3 of Nannochloropsis ; When the water quality turns light green, within 5-12 days before seedling raising, inoculate the pond with ultramicroscopic rotifers with a long diameter of no more than 140μm and a short diameter of no more than 100μm. The inoculation is divided into 3 times, and the inoculation amount is 1-2 billion rotifers with good vitality each time. Inoculate once every 24 hours. After the last inoculation, check the number of rotifers in the pond 24 hours after the last inoculation. When the number of rotifers per liter of seawater is greater than 100, prepare for seedling raising. During the seedling raising process, the water temperature cannot be lower than 22℃; S4. Breeding of grouper: Place the sterilized fertilized eggs in a hatching bag, fill the hatching bucket with clean seawater and add povidone iodine with a final concentration of 5 ppm of effective iodine, then place the hatching bag in the hatching bucket and let it stand for 15 minutes under aeration; fry will start to eat external food 48-72 hours after hatching, and prepare to open the hatching bag before dawn; 12 hours before opening the hatching bag, sprinkle no less than 1×10 5 cfu / m 3 Yeast, not less than 1×10 6 cfu / m 3 of lactic acid bacteria, not less than 1×10 5 cfu / m 3 of flat algae, and no less than 1ppm of glucose to strengthen the rotifers in the pond; 1 hour before opening the hatching bag, inject 0.5ppm vitamin C, 0.1ppm vitamin E, 0.5ppm astragalus polysaccharide, and 1ppm glucose into the hatching bag, and inject 0.1ppm vitamin C, 0.02ppm vitamin E, and 1ppm glucose into the pond outside the hatching bag; then, open the hatching bag and let the fry slowly swim into the pond; 12 days before opening the bag, inject 0.02-0.04ppm of urea every day, 0.5ppm glucose and 0.005-0.01ppm potassium dihydrogen phosphate maintain the algae phase and keep the water transparency between 30-90cm; Starting from the 7th day after opening, 0.1-0.5ppm solid chlorine dioxide particles, 0.1-0.3ppm astragalus polysaccharide, 0.5-1ppm glucose, 0.005-0.01ppm vitamin C, 0.005-0.01ppm taurine, and 1ppm polybasic organic acid were added to the pond every day and evenly sprinkled throughout the pond. In addition, no less than 1×10 5 cfu / m 3 photosynthetic bacteria; After 7 days of hatching, start feeding artificially hatched brine shrimp larvae. The initial feeding amount is 1000g of brine shrimp larvae hatched from dormant eggs. After 2 hours of feeding, use a 100-mesh dredger to enrich seawater at the feeding site. If the number of brine shrimp larvae remaining in 100L of seawater is less than 20, it is considered to have eaten. Double the feeding the next day until the number of brine shrimp larvae remaining in 100L of seawater is greater than 20. Maintain the feeding amount. When the feeding amount is insufficient again, increase the feeding amount by 20% every day thereafter until the fry are 20 days old. Starting from the 20th day after the fish start to fish, start feeding sword Daphnia with a long diameter of 0.5-2mm, mixed with brine shrimp larvae, and increase the amount of sword Daphnia by 20% every day until the sword Daphnia completely replaces the brine shrimp larvae. After the bait conversion is completed, continue to feed sword Daphnia until the fry complete the metamorphosis and become juveniles. In the later stage of seedling rearing, check whether the bait is sufficient by salvaging every day, and increase the feeding amount of the next day according to the remaining amount of biological bait until the fry complete the metamorphosis.

2. The method for raising grouper in low-position ponds according to claim 1, characterized in that: In step S4, before the release of sword Daphnia, it is necessary to strengthen the hatching bucket. The strengthening method is as follows: after the hatching bucket is filled with seawater, no less than 1×10 5 cfu / m 3 of lactic acid bacteria, not less than 1×10 5 cfu / m 3 brewer's yeast, 10ppm fish oil, 10ppm shrimp meal, 1ppm Schizochytrium, 0.5ppm vitamin C, 0.02ppm vitamin E, 0.01ppm vitamin A and 0.01ppm folic acid, and aerate vigorously, put the insect bodies into the hatching bucket, the dead insect bodies will rise to the surface with the bubbles to form foam, remove the foam every 10-20 minutes, and the strengthening time is 2-5h.

3. The method for raising grouper in low-position ponds according to claim 1, characterized in that: In step S4, before placing the fertilized eggs into the hatching bags, 500 ppm of photosynthetic bacteria, 5 ppm of polybasic organic acid, 5 ppm of disodium ethylenediaminetetraacetate, and 5 ppm of 100-mesh activated carbon powder are added to each hatching bag.

4. The method for raising grouper in low-position ponds according to claim 1, characterized in that: In step S3, the disinfection method is as follows: use a water truck to mix the bleaching powder in the pond, disinfect the water body for 48 hours, use 0.2-0.6ppm copper acetate to disinfect the water environment, and after 48 hours of copper acetate disinfection, use 3-5ppm polybasic organic acid and 0.5-1ppm disodium ethylenediaminetetraacetic acid to detoxify the water body for 48 hours.

5. The method for raising grouper in low-position ponds according to claim 1, characterized in that: In step S1, pond disinfection is carried out according to the following steps: seal the pond drain, place the water inlet of the high-pressure water gun in a bucket containing bleach, and use a water gun with a pressure of 0.3-0.5 bar to oxidize and disinfect the bottom and wall of the pond; after the disinfection is completed, use a water gun with a pressure of 0.3-0.5 bar to draw clean seawater to clean the entire pond.

6. The method for raising grouper in low-position ponds according to claim 1, characterized in that: In step S1, the pond cleaning operation is carried out as follows: use a high-pressure water gun with a pressure of not less than 2 bar to clean the pond, and use the high-pressure water gun to gradually turn over the sand from the center of the pond to the pond wall until the sand shows its original color and no organic matter and other impurities are attached to the surface of the coral stone; after cleaning, use a water gun with a pressure of 0.3-0.5 bar to rinse the sand bottom and coral stone flat.

7. The method for raising grouper in low-position ponds according to claim 5, characterized in that: In step S1, the bleaching liquid is prepared as follows: 800L of seawater is placed in a 1-ton wide-mouthed bucket, bleaching powder is filtered through a 40-mesh screen, the bleaching powder is gradually dissolved in the bucket, and the mixture is stirred thoroughly. The insoluble residue in the filter screen is discarded to obtain the bleaching liquid.

8. The method for raising grouper in low-position ponds according to claim 7, characterized in that: In step S1, the dosage of bleaching powder is 20 kg per mu; the disinfection time is in the evening when the light is weak.

9. The method for raising grouper in low-position ponds according to claim 1, characterized in that: In step S4, the method of placing photosynthetic bacteria is as follows: the photosynthetic bacteria are placed in a 1-ton incubation bucket, a 6-8 mm diameter hose with a lead weight is connected to the bottom of the incubation bucket and hung down to the bottom of the pond, the photosynthetic bacteria are driven into the bottom of the pond, and the photosynthetic bacteria are slowly covered with water flow until the metamorphosis is completed on the 30th day.

10. The method for ecological seedling raising of grouper in low-position ponds according to claim 4, characterized in that: In step S3, the usage amount of the bleaching powder is 10-15 ppm.

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