Indoor large-scale amplification culture method for moina mongolica

Abstract

The invention relates to the technical field of aquatic bait culture, in particular to an indoor large-scale amplification culture method for moina mongolica. Comprising the steps that an oxygen pipe, a temperature control pipe and an air stone are arranged in a culture pond, a double-oxygen oxygenation system is placed in the middle, and an incandescent lamp is arranged above; disinfecting and scrubbing facilities in the pool and pool walls with bleaching water; sequentially carrying out rough filtration, fine filtration and ultraviolet disinfection on external seawater, mixing the external seawater with tap water, adjusting the salinity to 15-20, and adding a sodium hypochlorite solution for disinfection; performing detoxification with sodium thiosulfate; screening and expanding germplasm of the moina mongolica by using a 50-60-mesh bolting-silk net; inoculating moina mongolica in the culture water body according to the density of 5500-6500 moina mongolica per liter; environment and water quality parameters are manually regulated and controlled after inoculation; the concentrated nannochloropsis oculata and the yeast are mixed for feeding, and when the daphnia magna density reaches 18000-23000 daphnia magna / L, all the daphnia magna is harvested at a water outlet. The method has the advantages that the daphnia body amplification density is high, and the amplification period is shortened; and pathogenic microorganisms are few.

Description

Technical Field

[0001] This invention relates to the field of aquatic feed culture technology, and in particular to a method for large-scale indoor amplification and culture of Daphnia mongolica. Background Technology

[0002] Mongolian naked-belly daphnia ( Moina mongolica Belonging to the order Craniopoda, subclass Branchiopoda, and class Crustacea, it is widely used as a high-quality live food for marine fish and crustacean seedlings due to its rapid reproduction, rich essential fatty acids and high protein content. In recent years, its importance in the seedling industry has become increasingly prominent. However, the large-scale expansion technology of Daphnia mongholica has always been hampered by bottlenecks, making it difficult to meet the demand for stable and efficient supply of high-quality food in industrial seedling production. The specific problems are concentrated in two major technical directions: traditional aquaculture and existing intensive aquaculture. (1) In the traditional open-air expansion model, the aquaculture process is highly dependent on natural light, ambient temperature and natural dissolved oxygen conditions in the water, and has extremely poor resistance to weather fluctuations. This directly leads to low amplification efficiency of Daphnia mongholica - the density of Daphnia can only be maintained at 300-500 cells / L, and the complete amplification cycle takes more than 10 days; at the same time, the open-air aquaculture facilities lack effective water disinfection methods, and pathogenic microorganisms such as Vibrio and Trichodina are prone to proliferate and spread in the water, which significantly increases the risk of pathogens carried by the produced feed. Among them, the amount of Vibrio detected often exceeds 600 CFU / g, which seriously threatens the survival and health of larvae in the seedling stage. (2) In the existing intensive aquaculture technology, the relevant technical solutions still have obvious defects and have failed to achieve true indoor factory-scale aquaculture. For example, patent application CN102972357A, published on March 20, 2013, entitled "An Intensive Production Method for Daphnia Mongolianis," although adopting improved measures such as cement pond culture and artificial aeration, is essentially still a partial optimization of traditional earthen pond culture technology. It still relies on traditional methods such as Chlorella cultivation and organic fertilizer (such as chicken manure) feeding, resulting in a longer culture time and failure to break through the bottleneck in Daphnia density and expansion efficiency. Another type of patent application, such as CN101036447A, published on September 19, 2007, entitled "Seawater Acclimation and Indoor High-Density Culture Method of Daphnia Mongolianis," mentions that it can achieve high-density indoor culture, but in actual operation, it relies on a micro-flow water culture mode and requires the use of chemical agents such as formaldehyde to control water pollution. This is not only difficult to adapt to large-scale factory production scenarios, but the residual risks of chemical agents will also directly threaten the health of fish fry, failing to meet the core requirements of industrial seedling production for feed safety and supply stability.

[0003] Although existing indoor technology attempts to improve this situation by closed circulation water system, there are still obvious deficiencies in water body treatment, feeding strategy and oxygenation equipment. In summary, the current large-scale expansion technology of Mongolian daphnia has three fundamental defects: first, the traditional open-air or simple facility cultivation highly depends on the natural environment, with prominent problems of temperature and light fluctuation, uneven dissolved oxygen and pathogen pollution, resulting in low daphnia density, long expansion period (more than 10 days), low output purity and high risk of pathogen pollution (such as the detection amount of vibrio is more than 600 CFU / g). Although the indoor technology realizes high density (15000-20000 per / L), it depends on micro-flow water and formaldehyde to control pollution, which has chemical residue hidden dangers, threatens the safety of feed and seedling culture, and cannot match the high efficiency demand of seedling industry; second, the existing indoor intensive technology has system-level shortcomings, such as extensive water treatment method, lack of scientific feeding strategy, insufficient algal density (<200 million per / mL), inaccurate matching of yeast feeding amount to daphnia demand, and insufficient oxygenation equipment efficiency, which seriously restricts the cultivation efficiency; third, the pond and part of the semi-open cultivation mode have inherent defects, the open environment is easily polluted by external pathogenic microorganisms, and the key cultivation parameters such as temperature, light and dissolved oxygen are difficult to accurately and stably control, which not only leads to large fluctuation of feed quality, but also makes the nutritional value and disease resistance of daphnia itself decrease significantly, further increases the risk of carrying pathogenic bacteria, and hinders its large-scale application in industrial seedling culture.

[0004] Therefore, it is urgent to realize the indoor large-scale artificial cultivation of Mongolian daphnia, and promote the wide application and industrialization process of Mongolian daphnia in seedling industry. SUMMARY

[0005] The present application provides a method for indoor large-scale expansion and culture of Mongolian daphnia to solve the problems of low density, long period, high pathogen pollution and unstable feed quality in the existing cultivation of Mongolian daphnia.

[0006] The present application aims to provide a method for indoor large-scale expansion and culture of Mongolian daphnia, which specifically comprises the following steps: S1. Sterilization and disinfection preparation of the cultivation pond: an oxygen pipe, a temperature control pipe and an air stone are arranged in the cultivation pond, a double-oxygen oxygenation system is placed in the middle, and an incandescent lamp is arranged on the top; the facilities and walls in the pond are disinfected and brushed with bleach water, and then rinsed clean after standing for 1.5-3 hours; S2. Cultivation water preparation; specifically comprising: S21. The sea water is sequentially subjected to coarse filtration by a sand filter tank, fine filtration by an ultrafiltration device and ultraviolet disinfection and sterilization; S22. The treated sea water is mixed with tap water, and the salinity is adjusted to 15-20, and a sodium hypochlorite solution with a concentration of 8-12% is added for disinfection; S23. After disinfection, sodium thiosulfate is used for detoxification, and the treated water is used after aeration for 20-30 hours; S3. Germplasm prevention and pest control: the Daphnia magna germplasm is screened by using a 50-60 mesh silk screen, and the adult daphnia is screened and expanded; S4. Inoculation: inoculate the Daphnia magna in the water body at a density of 5500-6500 / L; after inoculation, artificially control the environment and water quality parameters; S5. Feeding: concentrated paramecium chlorella and high-sugar instant yeast are mixed for feeding, and the feeding frequency is 3-4 times a day; during each feeding, the density of the concentrated paramecium chlorella is controlled to be 20-40 million / ml, and the density of the high-sugar instant yeast is 100-150 mg / l; S6. Harvesting: when the daphnia density reaches 18000-23000 / L, all the daphnia are harvested at the drainage outlet.

[0007] Preferably, the bottom of the culture pond is a structure with a low middle and high periphery, and the water depth in the pond is 1-1.5 m; the water inlet of the culture pond is sleeved with a filter cotton bag for filtering the injected tap water.

[0008] Preferably, the culture pond adopts a circular blue PVC pond body with a volume of 25 m 3 , and the water depth in the pond is controlled to be 1.2 m; the double-oxygen aeration system comprises a nano oxygen disc with a diameter of 80 cm and one pure oxygen head; the number of the gas stones is 14, which are uniformly distributed in the culture pond; the number of the incandescent lamps is 4.

[0009] Preferably, the tap water in step S22 is filtered by a filter cotton bag and mixed with the treated seawater; the concentration of the sodium hypochlorite solution is 10%.

[0010] Preferably, during the expansion process of step S3, the water body condition and the body surface condition of the Daphnia magna are observed, and if pests appear, a formaldehyde solution with a concentration of 45-55% is used for killing, and the addition amount per ton of water body is 10-15 ml.

[0011] Preferably, the environment and water quality parameters are as follows: water temperature 24-29℃; dissolved oxygen 7-10 mg / L; pH 7.5-8.5; light intensity 5000-9000 lx, light cycle L:D=12h:12h; ammonia nitrogen content less than 0.02 mg / L, nitrite content less than 0.05 mg / L.

[0012] Preferably, the high-sugar instant yeast is added to water to prepare a solution, and the solution is filtered by a 100 mesh silk screen before being fed.

[0013] Preferably, the feeding time is 6-9 days.

[0014] Preferably, the Daphnia magna is harvested by using an 80 mesh silk screen in step S6.

[0015] Compared with the prior art, the present application can achieve the following beneficial effects: 1. High density and short cycle: by using the amplification culture method of the application, through optimizing the structure of the culture pond (circular PVC pond + nano oxygen disc + pure oxygen head double oxygen system) and environmental regulation (water temperature 24~29℃, illumination 5000~9000lx), adjusting the feeding strategy (mixed feeding of concentrated parvococcus and high sugar yeast), the amplification density reaches 18000~23000 / L, the amplification cycle is shortened to 6~9 days, the efficiency is increased by 3~6 times, and the average daily yield per unit of water is >260g / ton; 2. Low pathogen pollution and safety: using multiple disinfection processes of sand filtration, ultrafiltration, ultraviolet rays and sodium hypochlorite, combined with sodium thiosulfate detoxification, reducing pathogenic microorganisms (vibrio detection amount <20 CFU / g, traditional >600 CFU / g), eliminating the use of chemical agents in large-scale production, preventing and eliminating pests to improve purity, and ensuring bait quality and safety of seedling culture.

[0016] In summary, the indoor large-scale amplification culture method of Mongolian daphnia cany be controlled, free of chemical pollution, high density and stable Mongolian daphnia amplification, and provides efficient, safe and high-quality bait for the seawater seedling industry. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the flow chart of the indoor large-scale amplification culture method of Mongolian daphnia provided by the embodiment of the application. DETAILED DESCRIPTION

[0018] In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0019] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not constitute a limitation on the application.

[0020] The application provides an indoor large-scale amplification culture method of Mongolian daphnia, which specifically comprises the following steps: S1. Sterilization and disinfection preparation of culture pond: oxygen pipe, temperature control pipe and air stone are provided in the culture pond, a double-oxygen oxygenation system is placed in the middle of the culture pond, and an incandescent lamp is arranged above; the culture pond is respectively provided with a water inlet and a water outlet; the facilities and walls in the pond are disinfected and brushed with bleach water, and then rinsed clean after standing for 1.5~3 hours; Preferably, the bottom of the culture pond is a structure with low middle and high periphery, and the water depth is 1~1.5m; The water inlet of the culture pond is sleeved with a filter cotton bag for filtering the tap water injected; Specifically, the culture pond adopts a circular blue PVC pond body with a volume of 25 m 3 The water depth in the culture pond is controlled at 1.2 m; the double-oxygen aeration system includes a nanometer oxygen disc with a diameter of 80 cm and one pure oxygen head; the number of gas stones is 14, which are evenly distributed in the culture pond; the number of incandescent lamps is 4, and the power is 150 w.

[0021] S2. Preparation of culture water body: S21. The seawater is sequentially subjected to coarse filtration through a sand filter tank, precision filtration through an ultrafiltration device, and ultraviolet disinfection and killing; S22. The treated seawater is mixed with tap water, and the salinity is adjusted to 15-20, and a sodium hypochlorite solution with a concentration of 8-12% is added for disinfection; S23. After disinfection is completed, sodium thiosulfate is used for detoxification, and the water is used after aeration for 20-30 hours; Preferably, the tap water is filtered through a cotton bag and then mixed with the treated seawater; The concentration of the sodium hypochlorite solution is 10%; After detoxification, the water is used after aeration for 24 hours.

[0022] S3. Germplasm prevention and pest control: The Daphnia magna germplasm is screened using a 50-60 mesh silk screen, and the adult daphnia are selected for expansion; during the expansion process, the water body condition and the surface condition of the Daphnia magna are observed, and if pests are present, a formaldehyde solution with a concentration of 45-55% is used for killing; Preferably, the concentration of the formaldehyde solution is 50%, and the addition amount is 10-15 ml / ton of water body, which can be appropriately increased to 20-25 ml / ton of water body according to the pollution condition.

[0023] S4. Inoculation: The Daphnia magna is inoculated in the culture water body at a density of 5500-6500 individuals / L; after inoculation, the environment and water quality parameters are artificially controlled; during the artificial control process, beneficial bacteria are used, including photosynthetic bacteria (Q / 370902SBL009), EM bacteria (Q / 370902SBL232), lactic acid bacteria (Q / 370902SBL231), and nitrifying bacteria (Q / SY-Y / XH002); Specifically, the environment and water quality parameters are as follows: water temperature 24-29℃; dissolved oxygen 7-10 mg / L; pH 7.5-8.5; light intensity 5000-9000 lx, light cycle L:D=12 h:12 h; ammonia nitrogen content less than 0.02 mg / L, nitrite content less than 0.05 mg / L; Preferably, the light intensity is 5000-8000 lx.

[0024] S5. Feeding: concentrated Nannochloropsis and yeast are mixed for feeding, and the feeding frequency is 3-4 times per day; at each feeding time, the density of the concentrated Nannochloropsis is controlled at 20-40 million / ml, and the density of the yeast is 10-150 mg / l; at the same time, photosynthetic bacteria EM bacteria, lactic acid bacteria and nitrifying bacteria are fed; the photosynthetic bacteria are fed at 5 ml / ton, 3-4 times a day; the EM bacteria, lactic acid bacteria and digestive bacteria are fed at 5 ml / ton, once a day; Preferably, the yeast used is high-sugar type, i.e. fermentation yeast (product standard code: GB / T20886.1), and the density is 100-150 mg / l; the yeast is added to water to prepare a solution, which is filtered through a 100-mesh silk screen before feeding; the ratio of concentrated Nannochloropsis to yeast is 7:3; The feeding time is 6-9 days.

[0025] S6. Harvesting: when the density of the daphnia reaches 18,000-23,000 / L, all the daphnia are harvested at the drainage outlet; Specifically, the 80-mesh silk screen is used for harvesting.

[0026] Example 1 The present embodiment provides a method for indoor large-scale expansion culture of Mongolian daphnia magna, which specifically comprises the following steps: S1. Sterilization and preparation of the culture pond The basic conditions of the culture pond: in the present embodiment, the culture pond adopts a circular blue PVC pond body with a volume of 25 m 3 The water depth in the pond body is controlled at 1.2 m; the pond body is designed to facilitate water circulation and uniform oxygenation, and to reduce the risk of pollutant accumulation; the bottom of the pond body is designed as a structure with low middle and high periphery, which is conducive to the centralized cleaning of the sediment at the bottom of the pond and improves the management convenience of the culture pond.

[0027] The culture pond is equipped with an oxygen pipe and a temperature control pipe; the oxygen pipe is used for basic oxygenation, and the temperature control pipe can adjust the water temperature in the pond according to the needs to ensure the stability of the culture environment temperature; 14 air stones are uniformly distributed in each culture pond to further assist oxygenation and ensure the uniform distribution of dissolved oxygen in the water body; a nanometer oxygen disc with a diameter of 80 cm and a pure oxygen head are placed in the middle of the culture pond to form a double-oxygen oxygenation system, which can significantly improve the dissolved oxygen efficiency and meet the high demand of Mongolian daphnia magna for dissolved oxygen in high-density culture; four 150-w incandescent lamps are uniformly distributed above the pond to provide stable light conditions and facilitate the regulation of light intensity.

[0028] Before the breeding, all facilities and pool walls in the pool need to be disinfected and sterilized. The specific operation is as follows: use bleach water to brush and disinfect the facilities and pool walls in the pool. After brushing, stand for 2 hours to ensure that the bleach water fully plays a disinfecting role, then rinse the bleach water residue with clean water to avoid adverse effects on the subsequent breeding of Mongolian Daphnia magna. The inlet of the breeding pool is equipped with a filter cotton bag, which can preliminarily filter the impurities in the water entering the pool to ensure the water quality.

[0029] S2. Preparation of breeding water: The water used for breeding is mixed and adjusted by sea water and tap water. First, the sea water (taken from the natural environment) is treated multiple times, the specific steps are as follows: S21. Sea water treatment: First, the sand filter tank is used for coarse filtration to remove silt, large particles and other impurities in the sea water; the filtered sea water is then subjected to fine filtration in the ultrafiltration equipment to further remove small particles, colloids, plankton and other impurities in the water; the fine filtered sea water is subjected to ultraviolet disinfection treatment, which uses the bactericidal effect of ultraviolet rays to kill some pathogenic microorganisms in the water; S22. Mix the treated sea water with the filtered tap water through the filter cotton bag according to a certain proportion to adjust the salinity of the mixed water to 15~20, which is the suitable salinity for the growth and reproduction of Mongolian Daphnia magna; then add 10% sodium hypochlorite solution to the water with adjusted salinity for disinfection, which can effectively kill the residual pathogenic microorganisms in the water, further ensuring the cleanliness and safety of the water; S23. After disinfection, add sodium thiosulfate to the water for detoxification treatment to eliminate the residual toxicity of sodium hypochlorite, and finally expose the treated water to air for 24 hours to make the dissolved oxygen in the water reach a saturated state, while removing any harmful gases that may exist in the water, after which the water can be introduced into the breeding pool for the breeding of Mongolian Daphnia magna.

[0030] S3. Germplasm prevention and pest control To ensure the purity of the inoculated Mongolian Daphnia magna germplasm, the purchased or collected Mongolian Daphnia magna germplasm needs to be purified before inoculation. First, use a 50~60 mesh silk screen to screen the Mongolian Daphnia magna germplasm, and select the daphnia. This screening step can remove larger pests such as chironomus to avoid competition for living space and nutritional resources between the pests and Mongolian Daphnia magna, affecting the growth and reproduction of Mongolian Daphnia magna; the screened Mongolian Daphnia magna is expanded, and the water conditions and Mongolian Daphnia magna surface conditions are closely observed during the expansion process to check for the presence of rotifers and aggregating worms and other pests; if the above pests are found, use a 50% formaldehyde solution to kill the pests, with an addition of 10~15 ml per ton of water; formaldehyde solution can effectively kill rotifers, aggregating worms and other pests, and has little effect on Mongolian Daphnia magna at a reasonable concentration, ensuring the purity of the Mongolian Daphnia magna germplasm and laying a good foundation for subsequent large-scale expansion.

[0031] S4. Inoculation Mogurnda wangi is inoculated in the breeding water body, and the inoculation density is controlled at 5500-6500 pieces / L, which can not only ensure sufficient growth space for Mogurnda wangi, but also realize subsequent high-density expansion; during the whole breeding process, the water quality parameters of the breeding environment are maintained within the appropriate range through artificial regulation and control, and the specific parameter requirements are as follows: the water temperature is controlled at 24-29℃, which promotes the metabolism of Mogurnda wangi and speeds up the growth and reproduction speed; the dissolved oxygen is maintained at 7-10 mg / L, which meets the oxygen demand of Mogurnda wangi in high-density breeding, and the stable control of dissolved oxygen can be realized through the double-oxygen oxygenation system; the pH value is adjusted to 7.5-8.5, which is in line with the survival habits of Mogurnda wangi and avoids the adverse effects of high or low pH value on its growth; the light intensity is controlled at 5000-8000 lx, and the light cycle is set as L:D=12h:12h, which simulates the natural light conditions and provides an appropriate light environment for the growth and reproduction of Mogurnda wangi; at the same time, the ammonia nitrogen content is strictly controlled below 0.02 mg / L, and the nitrite content is below 0.05 mg / L, to prevent the accumulation of ammonia nitrogen and nitrite from having toxic effects on Mogurnda wangi.

[0032] S5. Feeding Concentrated paracoccus luteus and yeast are mixed and fed to provide Mogurnda wangi with sufficient and balanced nutrition; concentrated paracoccus luteus is rich in nutrients such as protein and vitamins, and yeast can provide rich amino acids and energy, so mixed feeding can meet the nutritional needs of Mogurnda wangi at different growth stages and improve its disease resistance and growth speed.

[0033] The feeding frequency is 3-4 times a day, and the density of concentrated paracoccus luteus is controlled at 2-4 million pieces / ml and the density of yeast is controlled at 10-150 mg / L during each feeding; the yeast used in this embodiment is high-sugar instant yeast, which meets the GB / T20886.1 standard and is purchased from Guangxi Danbaoli Yeast Co., Ltd. Before feeding the yeast, the corresponding mass of yeast is calculated and weighed according to the volume of the water body in the breeding pond and the required yeast density, and the yeast is added to tap water to prepare a solution, which is then filtered through a 100-mesh silk screen and fed, the filtering step can remove impurities and lumps in the yeast to avoid clogging the facilities in the breeding pond, while ensuring that the yeast can be uniformly dispersed in the water body for Mogurnda wangi to eat; the whole culture process lasts for 6-9 days, during which the feeding amount is adjusted appropriately according to the growth of Mogurnda wangi and the remaining amount of feed in the water body, to ensure sufficient feed supply without excess, and prevent feed residues from polluting the water body.

[0034] S6. When the density of Daphnia magna in the culture pond reaches 18000-23000 pieces / L, the harvesting operation can be performed; when harvesting, 80-mesh silk screen is used at the drain outlet of the culture pond to perform full harvesting, and the pore size of the 80-mesh silk screen is appropriate, which can not only ensure that Daphnia magna is fully intercepted and harvested, but also enable the culture water to be smoothly discharged.

[0035] The harvested Daphnia magna can be directly used as feed for seawater breeding, such as feeding leopard goniopsis fish fry. It has been verified through experiments that the survival rate of leopard goniopsis fish fry after hatching for 20 days can be increased to 58-63% when the Daphnia magna amplified by the method of the present application is used as feed, while the survival rate of fish fry is usually less than 35% when the feed bred by the traditional method is used as feed; at the same time, the disease rate of the fish fry is reduced to 1.7-2.9%, and the daily yield per unit of water body can reach more than 260g, which is significantly better than the traditional breeding method.

[0036] Example 2-4 The steps are the same as in Example 1, except that: in Examples 1-4, four 25m 3 blue PVC round ponds with a water depth of 1.2m are used for continuous culture for 8 days; the initial densities are 6023 pieces / L, 6461 pieces / L, 6198 pieces / L and 5683 pieces / L, respectively, and the final densities reach 19338 pieces / L, 23178 pieces / L, 20684 pieces / L and 18842 pieces / L, respectively. The growth and reproduction density of Daphnia magna after continuous culture for 8 days is shown in Table 1, and the harvesting condition is shown in Table 2.

[0037] Table 1 Growth and reproduction density of Daphnia magna after continuous culture for 8 days

[0038] Table 2 Harvesting condition of Daphnia magna after continuous culture for 8 days

[0039] The results show that the culture density of Examples 1-4 after continuous culture for 8 days is all >18000 pieces / L, and the average daily yield per unit of water body is all >260g, which has short culture time, high yield, and can meet the demand for high-quality organisms in the fixed stage of hatching and breeding.

[0040] Comparative Example The culture steps of Comparative Examples 1-2 are the same as in Example 1, except that: in Comparative Example 1, the yeast is changed to marine red yeast (Q / 370902SBL065), and in Comparative Example 2, the yeast is changed to yeast extract (GB / T23530). Under different yeast feeding conditions (1, 2 and 3 parallel experiments are set for each group), the daily yield of Daphnia magna per unit of water body is measured to evaluate the effect of large-scale expansion culture. The results are shown in Table 3.

[0041] Table 3 Average daily yield (g / t / day) of different yeast units in water

[0042] The results show that, under the same concentration of Nannochloropsis oculata, the average daily yield of the three different types of yeast units in water is significantly different. The yield of the case group using the high-sugar instant yeast of Example 1 is significantly higher than that of the marine red yeast and the yeast extract group. The yield difference is due to the different types of yeast. In Table 3, the average yield of the high-sugar instant yeast group is about 280 g / t / day, the average yield of the marine red yeast group is about 228 g / t / day, and the average yield of the yeast extract group is about 194 g / t / day. The yield advantage of the high-sugar instant yeast reaches 30-45%. The above order of magnitude difference directly proves the high efficiency of the present application in promoting the reproduction of Mongolian daphnia. It shows that the use of high-sugar instant yeast for the large-scale expansion of Mongolian daphnia has better effect.

[0043] Application test example The Mongolian daphnia obtained in Examples 1-4 were subjected to breeding and feeding tests at Hainan Wenchang Haowangxing grouper breeding base. 10,000 indoor hatched 20-day-old Epinephelus fasciatomaculosus fry were released in each test group. During the breeding period, daily feeding management was carried out in accordance with the factory breeding technical specifications of Epinephelus fasciatomaculosus. Comparative examples 3-4 were fed with Chlorella purchased from an outdoor pond and daphnia cultured with fermentation feed. Comparative examples 5-6 were fed with Calanus and Cerodiapomus cultured with outdoor fermented chicken manure. The average detection level of pathogenic vibrio (wet weight) in the feed of the 8 examples was 18 CFU / g, 15 CFU / g, 20 CFU / g, 17 CFU / g, 676 CFU / g, 759 CFU / g, 873 CFU / g, and 805 CFU / g. After 15 days of breeding, white fry were harvested, and survival rate, morbidity, and body length were counted. The results are shown in Table 4.

[0044] Table 4 Epinephelus fasciatomaculosus fry breeding situation

[0045] The results show that, compared with the biological feed cultured in the outdoor pond, the pathogenic vibrio content of the Mongolian daphnia cultured indoors by the method of the present application is low, and the difference is obvious. Compared with comparative examples 3-6, the survival rate of the Epinephelus fasciatomaculosus bred in examples 1-4 is higher, the morbidity is lower, and the individual difference of the white fry is smaller, which shows that the use of the Mongolian daphnia obtained in examples 1-4 for feeding Epinephelus fasciatomaculosus fry in the hatching stage has higher survival rate and better fry quality.

[0046] It should be understood that the various forms of the flow shown above can be reordered, added to, or deleted from without departing from the scope of the present disclosure. For example, the steps recorded in the present disclosure can be executed in parallel, in sequence, or in different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0047] The foregoing detailed description has set forth various embodiments of the devices and / or processes via the use of specific terminology. However, embodiments thereof can be practiced with the exact description not being presented in detail. The term "device" should be understood to encompass devices operating in various modes, such as active mode, sleep mode, hibernate mode, and the like. The terms "coupled" and "connected," along with their derivatives, can be used. It should be understood that these terms are not intended as synonyms for each other. Rather, particular circuitry that can be said to be coupled or connected can be coupled and connected via some transmission medium.

Claims

1. A method for large-scale indoor amplification and culture of *Daphnia mongolica*, characterized in that: Specifically, the steps include the following: S1. Preparation for disinfection and sterilization of aquaculture ponds: Equip the aquaculture ponds with oxygen pipes, temperature control pipes and air stones, place a hydrogen peroxide aeration system in the middle, and install incandescent lamps above; disinfect and scrub the facilities and walls of the pond with bleach, let it stand for 1.5 to 3 hours, and then rinse it clean. S2. Preparation of aquaculture water; specifically including: S21. The seawater is sequentially filtered through a sand filter tank for coarse filtration, an ultrafiltration device for fine filtration, and ultraviolet disinfection. S22. Mix the treated seawater with tap water, adjust the salinity to 15-20, and add a sodium hypochlorite solution with a concentration of 8-12% for disinfection; S23. After disinfection, detoxify with sodium thiosulfate and use after aeration for 20-30 hours; S3. Germplasm prevention and pest control: Use a 50-60 mesh silk screen to screen the germplasm of Daphnia mongholica, and screen out the adult Daphnia for propagation; S4. Inoculation: Inoculate the aquaculture water with Daphnia mongholica at a density of 5500~6500 cells / L; after inoculation, artificially adjust the environmental and water quality parameters; S5. Feeding: Use a mixture of concentrated *Pseudomonas aeruginosa* and high-sugar instant yeast for feeding, with a feeding frequency of 3-4 times per day; each time, control the density of concentrated *Pseudomonas aeruginosa* at 2-4 million cells / ml and the density of high-sugar instant yeast at 100-150 mg / l. S6. Harvesting: When the density of Daphnia reaches 18,000 to 23,000 cells / L, harvest all of them at the drainage outlet.

2. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 1, characterized in that: The bottom of the breeding pond has a structure that is low in the middle and high around the edges, and the water depth inside the pond is 1 to 1.5 meters. The water inlet of the breeding pond is fitted with a filter cotton bag to filter the injected tap water.

3. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 2, characterized in that: The aquaculture pond has a volume of 25m³. 3 The pool is a circular blue PVC pool with a water depth controlled at 1.2m. The oxygenation system includes an 80cm diameter nano oxygen disc and a pure oxygen head. There are 14 air stones evenly distributed in the pool. There are 4 incandescent lamps.

4. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 2, characterized in that: In step S22, the tap water is filtered through a filter bag and then mixed with treated seawater; the sodium hypochlorite solution has a concentration of 10%.

5. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 1, characterized in that: During the expansion process in step S3, observe the water condition and the surface condition of the Mongolian naked-bellied daphnia. If pests appear, kill them with a formaldehyde solution with a concentration of 45-55%, adding 10-15 ml per ton of water.

6. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 1, characterized in that: The specific environmental and water quality parameters are as follows: water temperature 24~29℃; dissolved oxygen 7~10mg / L; pH 7.5~8.5; light intensity 5000~9000lx, photoperiod L:D=12h:12h; ammonia nitrogen content less than 0.02mg / L, nitrite content less than 0.05mg / L.

7. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 1, characterized in that: High-sugar instant yeast was added to water to prepare a solution, which was then filtered through a 100-mesh silk screen before being fed to the yeast.

8. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 1, characterized in that: The feeding period is 6 to 9 days.

9. The method for large-scale indoor amplification and culture of *Daphnia mongolica* according to claim 1, characterized in that: In step S6, Mongolian naked-bellied daphnia is harvested using an 80-mesh silk screen.

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