A recirculating aquaculture system and method for inhibiting sexual precocity in hermit crabs

Abstract

This invention discloses a recirculating aquaculture system and method for inhibiting precocious puberty in juvenile crabs. The system utilizes a combination of adjustable-spectrum LED lighting to regulate the light environment, multi-layered annular habitat components to disperse stocking density, and multi-stage closed-loop recirculating water treatment to stabilize water quality. Simultaneously, a long photoperiod inhibits gonadal development without suppressing body growth; precise nutrient formulation satisfies normal growth while delaying ovarian development; periodic variable-flow movement increases energy consumption, reduces fat accumulation, and strengthens muscles and appendages; and high-frequency grading and screening not only avoids cannibalism caused by individual differences but also achieves precise nutritional control within groups, promoting uniform size across the entire system. The entire system is a closed loop, resulting in fewer diseases, no drug use, and high ecological efficiency. It can reduce the precocious puberty rate of juvenile crabs to below 5%, achieve a uniform size at harvest (over 85%), and increase the survival rate by more than 30% compared to traditional earthen ponds.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, specifically to a recirculating aquaculture system and method for inhibiting precocious puberty in juvenile crabs. Background Technology

[0002] Juvenile crabs refer to the Chinese mitten crabs that have undergone metamorphosis from megalopause and have been cultured for approximately 5-7 months, reaching a size of 100-200 crabs per kilogram. Their quality directly affects the yield and size of adult crabs cultured the following year. Currently, juvenile crab farming mainly relies on earthen ponds, which generally face the following challenges: a high rate of precocious sexual maturity. In traditional earthen ponds, due to the uncontrollable factors such as light, nutrition, and accumulated temperature, approximately 20%-35% of juvenile crabs reach sexual maturity in the autumn of the same year, becoming "small green crabs." These crabs cannot molt and grow normally the following year, losing their continued aquaculture value and causing significant economic losses. Water quality is difficult to control precisely. Earthen pond water is greatly affected by weather, and ammonia nitrogen and nitrite levels are prone to exceed standards. Frequent water changes bring the risk of exogenous pathogens, and the use of drugs easily leads to drug residues.

[0003] Currently, although there are reports of suppressing precocious puberty by lowering water temperature or restricting nutrient intake, simply applying low temperature or low nutrition often inhibits growth simultaneously, resulting in juvenile crabs that are too small and do not meet the requirements for seedling production. Therefore, how to significantly reduce the rate of precocious puberty and improve size uniformity and survival rate without significantly sacrificing growth is a bottleneck that the juvenile crab farming industry urgently needs to overcome. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems in the prior art and to provide a recirculating aquaculture system and method for inhibiting precocious puberty in juvenile crabs.

[0005] The technical solution adopted in this invention is as follows:

[0006] A recirculating aquaculture system for inhibiting precocious puberty in crabs includes a circular culture pond, an annular perching assembly fixedly installed in the inner cavity of the circular culture pond, an LED panel light located directly above the circular culture pond, and a recirculating water treatment unit located on the circular culture pond.

[0007] The annular habitat assembly includes an installation ring, which is fixed to the inner cavity of the circular breeding pond. The top of the installation ring is provided with a first annular corrugated tile, and the top of the first annular corrugated tile is fixedly installed with a second annular corrugated tile through a first support block. The top of the second annular corrugated tile is fixedly installed with a third corrugated tile through a second support block.

[0008] The circulating water treatment unit includes a solid-liquid separator, a moving bed biofilter, a protein separator, an ultraviolet sterilizer, and a circulating pump. The inlet of the solid-liquid separator is connected to the interior of the circular aquaculture pond through a water guide pipe.

[0009] Preferably, the first annular corrugated tile, the second annular corrugated tile, and the third annular corrugated tile are all composed of multiple arc-shaped corrugated tiles.

[0010] Preferably, the solid-liquid separator, moving bed biofilter, protein separator, ultraviolet sterilizer, and circulation pump are connected in sequence through a water guide pipe, and the outlet of the circulation pump is connected to a drain pipe, one end of which extends into the interior of the circular aquaculture pond.

[0011] Preferably, the bottom of the circular aquaculture pond is conical with a slope of 5°-8°, and a sewage pipe is connected to the bottom of the circular aquaculture pond.

[0012] Preferably, the recirculating aquaculture system described above is used for the recirculating aquaculture of juvenile crabs, comprising the following steps:

[0013] S1. System preparation and release of young crabs: Inject fresh water into the breeding pond with a salinity of less than 0.5‰, run the circulating water treatment unit, and ensure that the ammonia nitrogen in the water is less than 0.2 mg / L and the nitrite is less than 0.02 mg / L; release the young crabs into the breeding pond at a density of 800-1200 crabs / square meter.

[0014] S2. Photoperiod Induction: From the date of deployment, a long photoperiod lighting system of 16 hours of light and 8 hours of darkness is adopted, with the light intensity maintained at 800-1500 lux and the spectral ratio of red light 60%-70%, blue light 20%-30%, and green light 5%-10%.

[0015] S3. Precision Nutrition Feeding: Feed twice daily, with a crude protein content of 30%-36%, crude fiber content of 10%-12%, and fat content of 4%-5%, and add 0.5% γ-aminobutyric acid and 0.3% taurine; the daily feeding amount is 3%-5% of the total body weight of the crab.

[0016] S4. Variable flow stimulation: Set two water flow periods each day, each lasting 2 hours. During the water flow period, the water flow velocity in the pool is maintained at 0.2-0.3 m / s; during the remaining time, the water flow velocity is maintained at 0.05-0.08 m / s.

[0017] S5. Regular grading and screening: Starting from the 30th day after the release of the juvenile crabs, the cultured population is screened every 15 days using a grading sieve. The juvenile crabs with an individual weight >0.13g are transferred to another culture pond with the same environmental conditions and fed separately with feed containing 30% protein, while maintaining the same photoperiod. The remaining juvenile crabs continue to be cultivated in the original pond.

[0018] Preferably, throughout the entire aquaculture process, the water temperature is maintained at 24±1℃, dissolved oxygen is greater than 6 mg / L, pH is 7.5-8.5, the bottom of the aquaculture pond is drained once a week, and water quality indicators are monitored daily.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. This invention utilizes LED panel lights with independently adjustable tri-color spectrum and photon flux density to customize light intensity and duration according to the crab breeding cycle, avoiding strong light and unreasonable spectrum stimulation that could induce precocious puberty. The annular habitat component divides the space into multiple layers, dispersing local breeding density. Corrugated tiles with a diatomaceous earth biomimetic coating conform to the crab's climbing habits, reducing stress responses caused by competition for food and space. This addresses the two core factors of light and habitat environment that inhibit precocious puberty. The multi-stage series-connected circulating water treatment unit, combined with a conical bottom tangential return structure, can quickly separate and degrade uneaten feed and feces, purify organic matter in the water, and kill pathogens. The closed-loop circulation throughout the process reduces external water replacement, stabilizes ammonia nitrogen and nitrite levels, avoids water quality fluctuations that could exacerbate stress in crabs, reduces the dual risks of disease and precocious puberty, reduces drug use, and avoids drug residue problems.

[0021] 2. Combining the recirculating aquaculture system of this invention, the method of this invention resolves the contradiction of small size caused by low temperature or low nutrition by inhibiting gonadal development without inhibiting body growth through long photoperiod; through precise nutrient ratio and the addition of functional amino acids, it delays the ovarian development process while meeting normal growth requirements; periodic variable flow increases energy consumption, reduces fat accumulation, and strengthens muscles and appendages, making the juvenile crabs more robust; and high-frequency grading and screening not only avoids cannibalism caused by individual differences, but also achieves precise nutritional regulation by grouping, promoting a more uniform size across the entire system. The entire system is a closed loop, with fewer diseases, no drug use, and high ecological efficiency. It can reduce the precocious maturity rate of juvenile crabs to below 5%, achieve a uniform size at harvest of over 85%, and increase the survival rate by more than 30% compared to traditional earthen ponds. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the recirculating aquaculture system in this invention.

[0023] Figure 2 This is a schematic diagram of the structure of the ring-shaped perching component of the present invention.

[0024] In the diagram: 1. Circular aquaculture pond; 2. Annular habitat assembly; 21. Mounting ring; 22. First annular corrugated tile; 23. First support block; 24. Second annular corrugated tile; 25. Second support block; 26. Third corrugated tile; 3. LED panel light; 4. Circulating water treatment unit; 41. Solid-liquid separator; 42. Moving bed biofilter; 43. Protein separator; 44. Ultraviolet sterilizer; 45. Circulating pump; 46. Water guide pipe; 47. Drainage pipe. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] A recirculating aquaculture system for inhibiting precocious puberty in juvenile crabs

[0028] like Figure 1-2 The recirculating aquaculture system shown includes a circular culture pond 1, an annular perching component 2 fixedly installed in the inner cavity of the circular culture pond 1, an LED panel light 3 located directly above the circular culture pond 1, and a recirculating water treatment unit 4 located on the circular culture pond 1.

[0029] The LED panel light 3 is fixed to the ground by a bracket. The LED panel light 3 is located directly above the center of the circular aquaculture pond, and the installation height is 1.2~1.8m above the water surface of the aquaculture pond.

[0030] LED panel light 3, whose driver module can accept PLC commands, independently outputs 660 nm red light, 450 nm blue light and 520 nm green light, and the maximum total photonic quantum flux density can be adjusted to 1500 μmol·m -2 ·s -1 ;

[0031] The annular perching component 2 includes an installation ring 21, which is fixed to the inner cavity of the circular breeding pond 1. The top of the installation ring 21 is provided with a first annular corrugated tile 22. The top of the first annular corrugated tile 22 is fixedly installed with a second annular corrugated tile 24 through a first support block 23. The top of the second annular corrugated tile 24 is fixedly installed with a third corrugated tile 26 through a second support block 25.

[0032] The first annular corrugated tile 22, the second annular corrugated tile 24, and the third annular corrugated tile 26 are all composed of multiple arc-shaped corrugated tiles;

[0033] The annular perching component 2 forms a stepped perching platform with a height difference of 15 cm between each layer;

[0034] The surface of the arc-shaped corrugated tile is coated with diatomaceous earth, with a roughness of Ra 25-50μm, simulating the surface of a natural reef, which makes it easier for crabs to climb and feed.

[0035] The circulating water treatment unit 4 includes a solid-liquid separator 41, a moving bed biofilter 42, a protein separator 43, an ultraviolet sterilizer 44, and a circulating pump 45. The inlet end of the solid-liquid separator 41 is connected to the interior of the circular aquaculture pond 1 through a water guide pipe 46.

[0036] The outlet of the solid-liquid separator 41 is connected to the inlet of the moving bed biological filter 42 through a conduit. The outlet of the moving bed biological filter 42 is connected to the inlet of the protein separator 43 through a conduit. The outlet of the protein separator 43 is connected to the inlet of the ultraviolet sterilizer 44 through a conduit. The outlet of the ultraviolet sterilizer 44 is connected to the inlet of the circulating pump 45. The outlet of the circulating pump 45 is connected to a drain pipe 47, one end of which extends into the interior of the circular aquaculture pond 1.

[0037] Solid-liquid separator 41 adopts a filter screen solid-liquid separation structure with a filter screen aperture of 80 mesh to intercept large particulate solid impurities such as residual bait and feces;

[0038] The filter bed is filled with suspended biological packing material to degrade ammonia nitrogen and nitrite in the water.

[0039] Protein separator 43 relies on bubble adsorption to remove soluble proteins and fine organic debris from water;

[0040] The UV sterilizer 44 is compatible with circulating water volume and kills pathogens in the water.

[0041] The bottom of the circular aquaculture pond 1 is conical with a slope of 5°-8°, and the bottom of the circular aquaculture pond 1 is connected to a sewage pipe;

[0042] The sewage pipe is equipped with a manual gate valve. The valve is closed during daily farming and opened during sewage discharge to centrally discharge accumulated sewage.

[0043] The water guide pipe 46 cuts from the pond wall to return water, creating a swirling flow that helps uneaten feed and feces gather towards the center. It is also compatible with the conical bottom drainage structure, resulting in higher cleaning efficiency.

[0044] The working principle of this practical application is as follows:

[0045] Operators use PLC to control the LED panel lights 3 installed above the circular breeding pond 1, independently adjust the output ratio of 660nm red light, 450nm blue light and 520nm green light, adjust the total photon flux density and day and night light duration, and set low-stimulation light parameters according to different breeding stages of juvenile crabs to avoid unreasonable light stimulation of juvenile crab gonads to develop prematurely.

[0046] The annular habitat component 2 is fixedly installed inside the circular breeding pond 1 by the mounting ring 21; the first annular corrugated tile 22 supports the second annular corrugated tile 24 with the help of the first support block 23, and the second annular corrugated tile 24 supports the third corrugated tile 26 with the help of the second support block 25. The three layers of corrugated tiles form a stepped habitat platform with a height difference of 15cm. The crabs can inhabit and feed autonomously in the layered arc-shaped corrugated tile area. The diatomaceous earth biomimetic coating on the surface of the corrugated tiles is adapted to the climbing habit. The layered structure disperses the local breeding density, reduces the stress response caused by competition for food and space, and inhibits precocious puberty from the perspective of habitat environment.

[0047] The water in the breeding pond is tangentially drawn out through the water pipe 46 and sent into the solid-liquid separator 41. The tangential water inlet will cause the water inside the circular breeding pond 1 to form a swirling flow. Uneaten feed and feces will collect along the swirling flow towards the center of the conical pond bottom and can be discharged periodically through the sewage pipe at the bottom of the pond.

[0048] The solid-liquid separator 41 first separates large solid wastes, and the effluent is transported to the moving bed biological filter 42 to degrade ammonia nitrogen and nitrite. After treatment, the water enters the protein separator 43 to remove soluble organic matter, and then flows through the ultraviolet disinfection device 44 to disinfect pathogens in the water. The qualified water is connected to the circulation pump 45 and returned to the circular breeding pond 1 through the drain pipe 47 to complete the closed-loop circulation. The cone-shaped pond bottom with a slope of 5°-8° further improves the efficiency of waste collection and sewage discharge, stabilizes water quality, avoids the problem of water quality fluctuations aggravating the stress of juvenile crabs, and reduces the incidence of precocious puberty in juvenile crabs in synergy with light regulation and stratified habitat structure.

[0049] Example 2

[0050] This example uses the recirculating aquaculture system of Example 1 to provide a method for inhibiting precocious puberty in juvenile crabs. It includes the following steps:

[0051] S1: System preparation and release of young crabs: On June 2, fresh water was injected into circular culture pond 1 with a salinity of less than 0.5‰. The circulating water treatment unit 4 was run, and the ammonia nitrogen in the water was less than 0.2 mg / L and the nitrite was less than 0.02 mg / L. The system was pre-run for 3 days to complete the biofilm formation. On June 5, 10,000 young crabs with an average weight of 4.5 mg, intact appendages and strong vitality were released into the culture pond at a density of 1,000 crabs / square meter.

[0052] S2: Photoperiod Induction: From the date of release, turn on LED panel light 3 and adopt a long photoperiod of 16 hours of light and 8 hours of darkness. The light intensity is maintained at 1000 lux, and the spectral ratio is 65% red light, 25% blue light and 10% green light. This long photoperiod environment inhibits the secretion of melatonin and continuously inhibits the initiation of gonadal development in juvenile crabs.

[0053] S3: Precision Nutrition Feeding: Feed twice a day (8:00 and 18:00), with crude protein content of 30% and 36% (different protein feeds are used after screening), crude fiber content of 10%, and fat content of 5%, and add 0.5% γ-aminobutyric acid and 0.3% taurine; the daily feeding amount is 4% of the total weight of the crab, and the specific amount is adjusted according to the amount of uneaten feed;

[0054] S4: Variable flow exercise stimulation: Two water flow exercise periods are set up every day (11:00-13:00 and 23:00-1:00), each lasting for 2 hours. During the entire water flow exercise period, the flow rate of the circulation pump 45 is increased to make the water flow velocity in the pool reach 0.25 m / s, and the water flow velocity is maintained at 0.06 m / s for the remaining time. The water flow stress is used to encourage the juvenile crabs to move and climb on the annular habitat component 2, reduce the accumulation of body fat, and further weaken the nutritional basis for gonadal development.

[0055] S5: Regular grading and screening: The first grading and screening was carried out on July 5th using a sieve with 5 mm mesh. Approximately 1800 larger individuals were screened out and transferred to a rearing pond of the same size, and fed a feed with 30% crude protein. Subsequently, before September 5th, the rearing population was screened every 15 days using a grading sieve. The larger individuals (approximately >0.13g) were transferred to another rearing pond with the same environmental conditions and fed a feed with reduced protein content to 30%, while maintaining the same photoperiod. Smaller individuals continued to be raised in the original pond, thereby controlling growth differences within two gradients and significantly reducing size dispersion.

[0056] S6: Environmental control: Throughout the aquaculture period, the water temperature is maintained at 24±1℃ through conventional heating or cooling systems, dissolved oxygen is greater than 6 mg / L, pH is 7.5-8.5, the bottom of the aquaculture pond is drained once a week, and water quality indicators are monitored daily.

[0057] By December 10th, a total of 8,350 juvenile crabs had been harvested, with a survival rate of 83.5%. A random sample of 500 crabs was examined, and only 18 of them were found to be precocious, with a precocity rate of 3.6%. The coefficient of variation in body weight was 18.2%, indicating high uniformity in size.

[0058] Example 3

[0059] This example uses the recirculating aquaculture system of Example 1 to provide a method for inhibiting precocious puberty in juvenile crabs. It includes the following steps:

[0060] S1: System preparation and release of young crabs: On June 1st, fresh water was injected into circular culture pond 1 with a salinity of less than 0.5‰. The circulating water treatment unit 4 was run, and the ammonia nitrogen in the water was less than 0.1 mg / L and the nitrite was less than 0.01 mg / L. The system was pre-run for 4 days, and the biofilm in the biological filter was mature. On June 5th, 12,000 young crabs with an average weight of 4.2 mg, intact appendages, and strong vitality were released into the culture pond at a density of 1,200 crabs / square meter.

[0061] S2: Photoperiod Induction: From the date of deployment, turn on LED panel light 3 and adopt a long photoperiod lighting system of 16 hours of illumination and 8 hours of darkness, maintain the light intensity at 1200 lux, and the spectral ratio is 70% red light, 20% blue light and 10% green light;

[0062] S3: Precision Nutrition Feeding: Feed twice a day (7:00 and 19:00), with crude protein content of 30% and 37% (different protein feeds are used after screening), crude fiber content of 10%, and fat content of 5%, and add 0.5% γ-aminobutyric acid and 0.3% taurine; the daily feeding amount is 5% of the total weight of the crab, and the specific amount is adjusted according to the amount of uneaten feed;

[0063] S4: Variable flow stimulation: Two water flow exercise periods are set up each day (10:00-12:00 and 22:00-24:00), each lasting 2 hours. During the entire water flow exercise period, the flow rate of the circulation pump 45 is increased to make the water flow velocity in the pool reach 0.30 m / s, and the water flow velocity is maintained at 0.08 m / s for the remaining time. The water flow stress is used to encourage the juvenile crabs to move and climb on the annular habitat component 2, reduce the accumulation of body fat, and further weaken the nutritional basis for gonadal development.

[0064] S5: Regular grading and screening: The first grading and screening was carried out on July 8th using a 6 mm mesh screen to screen out approximately 2000 larger individuals (individual weight >0.15g), which were then transferred to a rearing pond of the same size and fed a feed with 30% crude protein. Subsequently, before September 8th, the rearing population was screened every 15 days using a grading screen. The larger individuals screened out were transferred to another rearing pond with the same environmental conditions and fed a feed with reduced protein content to 30%, while maintaining the same photoperiod. The remaining individuals continued to be reared in the original pond, thereby controlling the growth difference within two gradients and significantly reducing size dispersion.

[0065] S6: Environmental control: Throughout the aquaculture period, the water temperature is maintained at 24.5±1℃ through conventional heating or cooling systems, dissolved oxygen is greater than 6 mg / L, pH is 7.5-8.5, the bottom of the aquaculture pond is drained once a week, and water quality indicators are monitored daily.

[0066] By December 10th, a total of 10,320 juvenile crabs had been harvested, with a survival rate of 86.0%. A random sample of 500 crabs showed only 14 individuals exhibiting precocious puberty, a precocious puberty rate of 2.8%; the coefficient of variation in body weight was 16.5%. At higher stocking densities, adjusting the sieve aperture can improve population uniformity, and supplementing with a slightly higher protein feed and increasing the feeding amount can still ensure good growth.

[0067] Compare with Example 1

[0068] A traditional earthen pond (5 mu in area, 1.2 m in water depth) was used. On June 5, 2026, the same batch of juvenile crabs as in Example 2 were introduced, with a density of 1000 crabs / m². They were fed commercial crab feed with a crude protein content of 38% daily, and the daily feeding amount was 6% of the total weight of the crabs. No light or temperature was controlled, and the water was exchanged naturally. No grading was carried out.

[0069] Results: When the animals were released from the pond on December 10, the survival rate was 52%, the precocious puberty rate was 27.4%, and the coefficient of variation in body weight was 35.6%.

[0070] Compare with Example 2

[0071] A traditional earthen pond (5 mu in area, 1.2 m in depth) was used. On June 5, 2026, the same batch of juvenile crabs as in Example 2 were introduced, with the density increased to 1500 crabs / m². The crabs were fed commercial crab feed with a crude protein content of 38% daily, and the daily feeding amount was 8% of the total weight of the crabs. No light or temperature was controlled, and the water was exchanged naturally without any grading.

[0072] Results: When the crabs were released from the pond on December 10, the survival rate was only 41.2%, the precocious puberty rate was as high as 35.8%, and the coefficient of variation in body weight was 42.3%. A large number of individuals showed extreme size differences, with small individuals (<8 g) accounting for 32% and large individuals (>20 g) accounting for 28%. Among them, the proportion of precocious "small green crabs" was particularly prominent, and their economic value was extremely low.

[0073] The specification and drawings of this invention are intended to be illustrative rather than restrictive. Based on this invention, those skilled in the art can make substitutions and modifications to some of the technical features without creative effort, and all such modifications are within the scope of protection of this invention.

Claims

1. A recirculating aquaculture system for inhibiting precocious puberty in juvenile crabs, comprising a circular culture pond, characterized in that, The inner cavity of the circular breeding pond is fixedly equipped with a ring-shaped perching component, an LED panel light is provided directly above the circular breeding pond, and a circulating water treatment unit is provided on the circular breeding pond. The annular habitat assembly includes an installation ring, which is fixed to the inner cavity of the circular breeding pond. The top of the installation ring is provided with a first annular corrugated tile, and the top of the first annular corrugated tile is fixedly installed with a second annular corrugated tile through a first support block. The top of the second annular corrugated tile is fixedly installed with a third corrugated tile through a second support block. The circulating water treatment unit includes a solid-liquid separator, a moving bed biofilter, a protein separator, an ultraviolet sterilizer, and a circulating pump. The inlet of the solid-liquid separator is connected to the interior of the circular aquaculture pond through a water guide pipe.

2. The recirculating aquaculture system according to claim 1, characterized in that, The first, second, and third annular corrugated tiles are all composed of multiple arc-shaped corrugated tiles.

3. The recirculating aquaculture system according to claim 1, characterized in that, The solid-liquid separator, moving bed biofilter, protein separator, ultraviolet sterilizer, and circulation pump are connected in sequence through a water guide pipe. The outlet of the circulation pump is connected to a drain pipe, and one end of the drain pipe extends into the interior of the circular aquaculture pond.

4. The recirculating aquaculture system according to claim 1, characterized in that, The bottom of the circular aquaculture pond is conical with a slope of 5°-8°, and a sewage pipe is connected to the bottom of the circular aquaculture pond.

5. A method for inhibiting precocious puberty in juvenile crabs through recirculating aquaculture, characterized in that, Using the recirculating aquaculture system according to any one of claims 1-4 for the recirculating aquaculture of juvenile crabs includes the following steps: S1. System preparation and release of young crabs: Inject fresh water into the breeding pond with a salinity of less than 0.5‰, run the circulating water treatment unit, and ensure that the ammonia nitrogen in the water is less than 0.2 mg / L and the nitrite is less than 0.02 mg / L; release the young crabs into the breeding pond at a density of 800-1200 crabs / square meter. S2. Photoperiod Induction: From the date of deployment, a long photoperiod lighting system of 16 hours of light and 8 hours of darkness is adopted, with the light intensity maintained at 800-1500 lux and the spectral ratio of red light 60%-70%, blue light 20%-30%, and green light 5%-10%. S3. Precision Nutrition Feeding: Feed twice daily, with a crude protein content of 30%-36%, crude fiber content of 10%-12%, and fat content of 4%-5%, and add 0.5% γ-aminobutyric acid and 0.3% taurine; the daily feeding amount is 3%-5% of the total body weight of the crab. S4. Variable flow stimulation: Set two water flow periods each day, each lasting 2 hours. During the water flow period, the water flow velocity in the pool is maintained at 0.2-0.3 m / s; during the remaining time, the water flow velocity is maintained at 0.05-0.08 m / s. S5. Regular grading and screening: Starting from the 30th day after the release of the juvenile crabs, the cultured population is screened every 15 days using a grading sieve. The juvenile crabs with an individual weight >0.13g are transferred to another culture pond with the same environmental conditions and fed separately with feed containing 30% protein, while maintaining the same photoperiod. The remaining juvenile crabs continue to be cultivated in the original pond.

6. The recirculating aquaculture method according to claim 5, characterized in that, Throughout the aquaculture process, the water temperature was maintained at 24±1℃, dissolved oxygen was greater than 6 mg / L, and pH was 7.5-8.

5. Wastewater was discharged from the bottom of the aquaculture pond once a week, and water quality indicators were monitored daily.

Images