A culture device for widespread midges and application thereof

Abstract

The application discloses a culture device for Mesocyclops leuckarti and application thereof, and belongs to the technical field of fish culture. The culture device for Mesocyclops leuckarti comprises a cylinder, a top cover and a bottom cover, the top cover is movably connected with the top of the cylinder, and the bottom cover is fixedly connected with the bottom of the cylinder; a collecting pipe is arranged in the cylinder, the upper portion of the collecting pipe is a silk screen, the lower portion of the collecting pipe is a closed pipe, and a first light source is arranged in the collecting pipe; a second light source and a third light source are arranged on the inner side of the cylinder, and a temperature regulator and an oxygenator are arranged on the lower portion of the inner side of the cylinder. The culture device can realize large-scale continuous high-density culture of Mesocyclops leuckarti, can be applied to preparation of a biological prevention and treatment device for fish white spot disease, can reduce the abundance of water body Paramoecium caudatum and thus reduce the probability of fish suffering from the white spot disease, can provide other food sources for the fish, is beneficial to growth and development of the fish, and enriches the aquatic food web.

Description

Technical Field

[0001] This invention belongs to the field of fish farming technology, specifically relating to a cultivation device for the widely distributed Chinese water flea and its application. Background Technology

[0002] Existing research indicates that parasites should be included in the food web. *Ichthyophthirius multifiliis* can infect various freshwater fish, causing white spot disease and spreading globally. *Ichthyophthirius multifiliis* is an obligate parasite belonging to the phylum Ciliates, and its life cycle consists of four main stages: Theront (predator), Trophont (trophozoite), Protomont (cyst precursor), and Tomont (cyst). The predator invades the host's epidermis and grows into a trophozoite (0.4-0.6 mm in diameter). Before attaching to a solid substrate, the trophozoite briefly swims freely, becoming a cyst precursor, which can then swim freely. Subsequently, the cyst precursor secretes a cyst wall, forming a cyst that attaches to the solid substrate. The cyst undergoes binary fission, producing numerous tomites, which then transform into predators, breaking through the cyst wall to find new fish hosts.

[0003] Current technologies employ physical or chemical methods to treat the free-swimming predators of Ichthyophthirius multifiliis (white spot disease) to control this disease. For example, raising the aquaculture water temperature to 28-30℃ can effectively prevent white spot disease, but this method is energy-intensive and costly, making it unsuitable for large-scale artificial aquaculture. Controlling the water flow rate in the aquaculture pond can reduce the parasitism rate of Ichthyophthirius multifiliis on fish, thus achieving the prevention and control of white spot disease, but this has the disadvantage of excessively high construction and investment costs. Using chemical drug preparations to prevent and control white spot disease can lead to drug resistance within the parasite population through repeated treatments, resulting in poor control effects. Summary of the Invention

[0004] In response to the above-mentioned prior art, the present invention provides a widely distributed Daphnia fasciata cultivation device and its application, which solves the problem of white spot disease in artificially bred fish from the perspective of biological control; on the one hand, it reduces the abundance of Ichthyophthirius multifiliis in the water, thereby reducing the probability of fish suffering from white spot disease; on the other hand, it provides fish with other food sources, which is beneficial to their growth and development and enriches the aquatic food web.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a widely distributed *Daphnia gracilis* culture device is provided, comprising a cylinder, a top cover, and a bottom cover. The top cover is movably connected to the top of the cylinder, and the bottom cover is fixedly connected to the bottom of the cylinder. A collection tube is provided in the cylinder, the upper part of which is a silk screen and the lower part is a closed tube. A first light source is provided in the collection tube. A second light source and a third light source are provided inside the cylinder, and a temperature regulator and an aerator are provided in the lower part of the cylinder.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the first light source is located in the center of the collecting tube, extending from the top to the bottom of the collecting tube; or, the first light source is located at the bottom of the collecting tube.

[0008] Furthermore, the collecting tube is movably connected to the center of the top cover, and the mesh size of the silk screen is 20 mesh.

[0009] Furthermore, an inlet pipe is installed on the top cover; a first outlet pipe and a second outlet pipe are installed on the bottom cover. Valves are installed at the connection points of the two outlet pipes and the bottom cover. A silk screen with a mesh size of 200 mesh is installed at the connection point of the first outlet pipe and the bottom cover.

[0010] Furthermore, a method for culturing the widely distributed *Zygium micranthum*, using the aforementioned *Zygium micranthum* culture device, specifically includes the following steps:

[0011] S1: Add water to the culture device for the widely distributed Chinese sword flea. Add 1-3g of brown sugar, 1-3g of spirulina powder and 4-6mL of EM bacteria per liter of water. Add 100-200 Chinese sword fleas. Control the water temperature at 15-20℃ and the pH at 6-8.5. Turn on the second and third light sources and cultivate for 5 days.

[0012] S2: Change the water, add 3-5g of brown sugar, 4-6g of spirulina powder and 7-9mL of EM bacteria per liter of water, and incubate for 3 days;

[0013] S3: Change the water again, add 4-6g of brown sugar, 7-9g of spirulina powder and 8-12mL of EM bacteria per liter of water, and culture until the density of Cyprinidaria fasciata reaches 800-1200 ind / L;

[0014] S4: Turn on the first light source, turn off the second and third light sources and keep them closed for 5-8 minutes. Then open the valve of the first outlet pipe to release water. Widely distributed Cyprinidaria with a diameter of less than 0.85 mm will accumulate in the lower part of the collection pipe, and widely distributed Cyprinidaria with a diameter of greater than 0.85 mm will accumulate in the lower part of the cylinder. Then output the widely distributed Cyprinidaria with a diameter of greater than 0.85 mm through the second outlet pipe.

[0015] S5: Add water again, adding 4-6g of brown sugar, 7-9g of spirulina powder and 8-12mL of EM bacteria per liter of water. Turn off the first light source and turn on the second and third light sources to continue culturing. Repeat step S4 when the density of the widely distributed Cyprinidaria reaches 800-1200 ind / L.

[0016] Furthermore, in step S1, the amount of brown sugar is 2g, the amount of spirulina powder is 2g, the amount of EM bacteria is 5mL, the amount of Cyprinus fasciatus is 150, the water temperature is 18℃, and the pH is 7.

[0017] In step S2, the amount of brown sugar is 4g, spirulina powder is 5g, and EM bacteria is 8mL;

[0018] In step S3, the amount of brown sugar is 5g, spirulina powder is 8g, and EM bacteria is 10mL; the density is 1000 ind / L.

[0019] Hold for 5 minutes in step S4;

[0020] In step S5, the amount of brown sugar is 5g, spirulina powder is 8g, and EM bacteria is 10mL; the density of the widely distributed Cyprinidaria is 1000 ind / L.

[0021] Furthermore, the above-mentioned cultivation device for the widely distributed Chinese water flea is applied in the preparation of a biological control device for white spot disease in fish.

[0022] Furthermore, the above-mentioned cultivation device for the widely distributed Chinese water flea was applied in the preparation of a biological control device for white spot disease in longfin gudgeon.

[0023] Furthermore, the effective density of Cynactus chinensis, which is widely distributed in the biological control device for white spot disease in longfin gudgeon, is 450-550 ind / L.

[0024] Furthermore, the biological control device for white spot disease in longfin gudgeon includes a culture device for the widely distributed Daphnia fasciata and a fish farming system. The fish farming system includes a farming pond, a microfilter, a return water tank, a circulation pump, a sterilizer, and a moving biological bed. The outlet of the moving biological bed is divided into two pipelines, one of which connects to the inlet pipeline of the Daphnia fasciata culture device, and the other connects to the inlet of the farming pond. The second outlet pipeline of the Daphnia fasciata culture device connects to the inlet of the farming pond, and the first outlet pipeline of the Daphnia fasciata culture device connects to the inlet of the microfilter. The outlet of the farming pond connects to the inlet of the microfilter, the outlet of the microfilter connects to the inlet of the return water tank, the outlet of the return water tank connects to the inlet of the circulation pump, the outlet of the circulation pump connects to the inlet of the sterilizer, and the outlet of the sterilizer connects to the inlet of the moving biological bed.

[0025] The beneficial effects of this invention are as follows: The *Cypripedium glomeratum* culture device of this invention is simple and easy to operate, and can be applied to the large-scale continuous high-density culture of *Cypripedium glomeratum*. Biological control is defined as "using organisms to suppress population density or the influence of specific pests, reducing or destroying them compared to other conditions." Biological control has been widely used in pest management in terrestrial agriculture, as well as in removing aquatic ectoparasites through related species. *Cypripedium glomeratum* is an effective natural biological filter against the prolific worm *Ichthyophthirius multifiliis*, preying on shed trophozoites and free-swimming cysts. The device of this invention cultivates *Cypripedium glomeratum* and applies it to fish farming systems susceptible to *Ichthyophthirius multifiliis*, increasing the abundance of *Cypripedium glomeratum* in the water and thus reducing the abundance of *Ichthyophthirius multifiliis*, thereby reducing the probability of fish developing white spot disease. Furthermore, fish feed on zooplankton and aquatic insects, enhancing their predation ability and enriching the aquatic food web. The introduction of *Cypripedium glomeratum* provides fish with other food sources, improving their foraging ability and promoting their growth and development. In addition, the present invention has relatively low application cost, is easy to operate, is environmentally friendly, and has wide applicability. Attached Figure Description

[0026] Figure 1 A longitudinal sectional view of a culture device for the widely distributed Chinese water flea;

[0027] Figure 2 A cross-sectional view of a culture device for the widely distributed Chinese water flea;

[0028] Figure 3 A schematic diagram of the bottom cover of a culture device for the widely distributed Chinese water flea;

[0029] The components include: 1. cylinder; 2. top cover; 3. bottom cover; 4. collection pipe; 5-1. first light source; 5-2. second light source; 5-3. third light source; 6. temperature regulator; 7. aerator; 8-1. first outlet pipe; 8-2. second outlet pipe.

[0030] Figure 4 This is a schematic diagram of a fish farming system;

[0031] Among them, 10. Widespread Daphnia fasciata cultivation device; 21. Culture pond; 22. Microfilter; 23. Return water tank; 24. Circulation pump; 25. Sterilizer; 26. Biological moving bed;

[0032] Figure 5 The images show the white spot disease status of longfin gudgeon before and after treatment with the broad-spotted water flea in Example 4; where a and b are before treatment with the broad-spotted water flea, and c is one week after treatment with the broad-spotted water flea. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0034] Example 1

[0035] A widely distributed Daphnia magna culture device 10, such as Figure 1-3 As shown, the device includes a cylinder 1, a top cover 2, and a bottom cover 3. The top cover 2 is movably connected to the top of the cylinder 1 via a snap-fit, but other methods of movable connection are also applicable to this invention. The bottom cover 3 is fixedly connected to the bottom of the cylinder 1 with glue, but other methods of fixed connection are also applicable to this invention. A collection tube 4 is provided in the cylinder 1, and the collection tube 4 is movably connected to the center of the top cover 2 via a snap-fit, but other methods of fixed connection are also applicable to this invention. The upper part of the collection tube 4 has a mesh-like support structure and is covered with a 20-mesh silk screen, while the lower part is an opaque closed tube. A PLC controller is provided outside the device. A first light source 5-1 is provided in the collection tube 4. The first light source 5-1 is an LED light strip, located in the center of the collection tube 4, extending from the top to the bottom of the collection tube 4. The wire connecting the first light source 5-1 is connected to the PLC controller and an external power supply through the central through-hole of the top cover 2. In another preferred embodiment, the first light source 5-1 is an LED bulb, located at the bottom of the collection tube 4, and the wire connecting the first light source 5-1 runs from the bottom to the top of the collection tube 4. The top cover 2 is connected to the PLC controller and external power supply through the central through hole; a second light source 5-2 and a third light source 5-3 (both LED bulbs) are installed on the cylinder 1, and the wires connecting the second light source 5-2 and the third light source 5-3 are respectively connected to the PLC controller and external power supply through the through holes on the cylinder 1; a temperature regulator 6 (a commercially available temperature regulator that can be connected to a PLC controller) and an aerator 7 (a commercially available aerator that can be connected to a PLC controller) are installed at the bottom of the cylinder 1, and the wires connecting the temperature regulator 6... The wires are connected to the PLC controller and external power supply through the through holes on the cylinder 1; the wires connecting the aerator 7 are also connected to the PLC controller and external power supply through the through holes on the cylinder 1; an inlet pipe is provided on the top cover 2; a first outlet pipe 8-1 and a second outlet pipe 8-2 are provided on the bottom cover 3, and valves are provided at the connection points of the two outlet pipes and the bottom cover 3, and both valves are connected to the PLC controller through wires; a silk screen is provided at the connection point of the first outlet pipe 8-1 and the bottom cover 3, and the mesh size of the silk screen is 200 mesh.

[0036] Example 2

[0037] A method for culturing the widely distributed Cyclops fasciatus, the specific steps of which are as follows:

[0038] S1: Add water to the culture device 10 for *Daphnia granatum* from Example 1. Add 2g of brown sugar, 2g of spirulina powder, and 5mL of EM bacteria per liter of water. Add approximately 150 *Daphnia granatum*. Maintain the water temperature at around 18℃ and the pH at around 7, at which point the *Daphnia granatum* has the strongest reproductive capacity. Turn on the second light source 5-2 and the third light source 5-3, maintaining 14 hours of light and 10 hours of darkness per day for 5 days of cultivation.

[0039] S2: Change the water, add 4g of brown sugar, 5g of spirulina powder and 8mL of EM bacteria per liter of water, and incubate for 3 days;

[0040] S3: Change the water again, add 5g of brown sugar, 8g of spirulina powder and 10mL of EM bacteria per liter of water, and culture until the density of Cyprinidaria fasciata reaches about 1000 ind / L.

[0041] S4: Turn on the first light source 5-1, turn off the second light source 5-2 and the third light source 5-3 for about 5 minutes. The body length of the widely distributed Cypriniformes ranges from 0.64 to 1.2 mm. The widely distributed Cypriniformes with a mesh size smaller than 20 mesh silk screen are induced to enter the collection tube 4 due to phototaxis. Then, open the valve of the first outlet pipe of the bottom cover 3 to release water and lower the water level. Among them, the widely distributed Cypriniformes with a size smaller than 0.85 mm are enriched in the collection tube 4, and the widely distributed Cypriniformes with a size larger than 0.85 mm are enriched in the lower part of the cylinder 1 and output through the second outlet pipe of the bottom cover 3.

[0042] S5: Add water again, add 5g of brown sugar, 8g of spirulina powder, and 10mL of EM bacteria per liter of water to continue culturing. Turn off the first light source 5-1, turn on the second light source 5-2 and the third light source 5-3 and maintain 14 hours of light and 10 hours of darkness per day. Subsequently, check the density of the widely distributed Cypripedia fasciata in the culture device every 2 days. When the density reaches about 1000 ind / L, repeat step S4 to introduce the widely distributed Cypripedia fasciata into the culture system.

[0043] Example 3

[0044] A biological control device for white spot disease in fish, such as Figure 4 As shown, the system includes a *Daphnia gracilis* culture device 10 and a fish farming system. The fish farming system includes a culture pond 21, a microfilter 22, a return water tank 23, a circulation pump 24, a sterilizer 25, and a moving biological bed 26. The moving biological bed 26 (i.e., a moving bed biofilm reactor) has two outlets: one connects to the inlet pipe of the *Daphnia gracilis* culture device 10, and the other connects to the inlet of the culture pond 21. The second outlet pipe 8-2 of the *Daphnia gracilis* culture device 10 connects to the inlet of the culture pond 21, and the first outlet pipe 8-1 of the *Daphnia gracilis* culture device 10 connects to the inlet of the microfilter 22. The outlet of the culture pond 21 connects to the inlet of the microfilter, the outlet of the microfilter connects to the inlet of the return water tank 23, the outlet of the return water tank 23 connects to the inlet of the circulation pump 24, the outlet of the circulation pump 24 connects to the inlet of the sterilizer 25, and the outlet of the sterilizer 25 connects to the inlet of the moving biological bed 26.

[0045] The workflow of the aquaculture system is as follows: Water enters the return water tank 23 through the microfilter 22, passes through the circulation pump 24, and then enters the sterilizer 25 to perform preliminary sterilization of the aquaculture water. Then, it enters the biological moving bed 26 and is discharged into the widely distributed Chinese sword flea culture device 10 and the aquaculture pond 21 respectively. The widely distributed Chinese sword flea culture device 10 and the aquaculture pond 21 are interconnected to facilitate the transportation of the widely distributed Chinese sword fleas. The widely distributed Chinese sword flea culture device 10 is connected to the microfilter 22 to enable water recycling.

[0046] When used for prevention, introduce *Cypripedium fasciatus* into pond 21 once a week at a density of 500 ind / L. This serves both a preventative purpose and provides the fish with a natural food source. When used for treatment, introduce *Cypripedium fasciatus* into pond 21 every three days at a density of 500 ind / L. After introduction, no water changes are needed in pond 21, as impurities are automatically removed through circulation.

[0047] Example 4

[0048] Treatment of longfin gudgeon with white spot disease outbreak in aquaculture system

[0049] (1) Shut down the circulating water in the longfin gudgeon aquaculture system;

[0050] (2) Add 3L of water to the culture device 10 for the widely distributed Chinese sword flea, then add 6g of brown sugar, 6g of spirulina powder and 15mL of EM bacteria, and finally add about 500 widely distributed Chinese sword fleas. Culture at 20℃ and pH 8. Collect when the density reaches about 1000 ind / L.

[0051] (3) Control the first light source 5-1, the second light source 5-2 and the third light source 5-3, and use phototaxis to collect the widely distributed Cyclops 0.85mm and transfer them to the culture water at a density of about 500 ind / L. The widely distributed Cyclops prey on the trophozoites and cysts of Ichthyophthirius multifiliis, and the trophozoites and cysts die after being attacked.

[0052] (4) Use a filtration device to extract 3L of water from the longfin gudgeon culture system every 24 hours and use 16S rRNA technology to detect the abundance changes of Ichthyophthirius multifiliis in the water. Randomly select longfin gudgeons to detect the Ichthyophthirius multifiliis load on the tail fins of the fish.

[0053] Specific test data are shown in Table 1. After releasing the widely distributed Cyclops hygrophorus into the water for one week, as... Figure 5 As shown, the small white spots on the surface of the longfin gudgeon disappeared, and no reinfection occurred. The circulating water system was turned on, and the gudgeon were fed for another week to promote feeding. This shows that the widely distributed Chinese water flea culture device 10 can be used to prepare a biological control device for treating white spot disease in longfin gudgeon.

[0054] Table 1. The therapeutic effect of *Cyprinus glomeratus* on Ichthyophthirius multifiliis infection in *Gnaphalium affine*.

[0055] Time (d) Ichthyophthirius multifiliis abundance (%) in water bodies Number of Ichthyophthirius multifiliis trophozoites on the fish's tail fin (individual 0 9.45 46 1 8.23 38 2 6.68 25 3 5.65 16 4 5.35 18 5 3.32 16 6 0.55 0 7 0.22 0

[0056] Example 5

[0057] Prevention of Ichthyophthirius multifiliis in longfin gudgeon

[0058] The control group and the experimental group were set up, and the specific grouping was as follows:

[0059] Control group: Longfin gudgeon + Widespread Water flea;

[0060] Experimental group 1: Longfin gudgeon + Ichthyophthirius multifiliis;

[0061] Experimental group 2 consisted of longfin gudgeon, widely distributed water flea, and multi-fed Ichthyophthirius multifiliis.

[0062] During the water conditioning period of the aquaculture system, *Daphnia fasciata* was cultured using a *Daphnia fasciata* culture device 10 to expand the population. *Daphnia fasciata* was introduced into the *Gromitra spp.* aquaculture system of the control group and experimental group 2 at a density of approximately 500 ind / L. At the same time, *Ichthyophthirius multifiliis* was introduced into the aquaculture system of experimental group 1 and experimental group 2 at a density of approximately 2000 individuals / animal. Two days later, *Gromitra spp.* were introduced into the aquaculture ponds of the control group, experimental group 1, and experimental group 2 at a density of 10 individuals / L. Thereafter, *Daphnia fasciata* was introduced into the aquaculture system of the control group and experimental group 2 at a density of approximately 500 ind / L every 3 days.

[0063] One week later, observation revealed that only fish in experimental group 1 were infected with Ichthyophthirius multifiliis, exhibiting small white spots. This indicates that introducing Daphnia fasciata into the fish farming system has a preventive effect against white spot disease in fish. The Daphnia fasciata culture device 10 can be used to prepare a biological control device for preventing white spot disease in gudgeon.

[0064] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A cultivation device for the widely distributed Chinese water flea, characterized in that: The widely distributed Chinese water flea culture device (10) includes a cylinder (1), a top cover (2) and a bottom cover (3). The top cover (2) is movably connected to the top of the cylinder (1), and the bottom cover (3) is fixedly connected to the bottom of the cylinder (1). A collection tube (4) is provided in the cylinder (1). The upper part of the collection tube (4) is a sieve silk screen, and the lower part is a closed tube. A first light source (5-1) is provided in the collection tube (4). A second light source (5-2) and a third light source (5-3) are provided inside the cylinder (1). A temperature regulator (6) and an aerator (7) are provided at the lower part of the inner side of the cylinder (1).

2. The cultivation device for the widely distributed Chinese water flea according to claim 1, characterized in that: The first light source (5-1) is located in the center of the collecting tube (4) and extends from the top end of the collecting tube (4) to the bottom end; or, the first light source (5-1) is located at the bottom end of the collecting tube (4).

3. The cultivation device for the widely distributed Chinese water flea according to claim 1, characterized in that: The collecting tube (4) is movably connected to the center of the top cover (2), and the mesh size of the silk screen is 20 mesh.

4. The widely distributed *Daphnia magna* culture device according to claim 1, characterized in that: An inlet pipe is provided on the top cover (2); a first outlet pipe (8-1) and a second outlet pipe (8-2) are provided on the bottom cover (3). Valves are provided at the connection points between the two outlet pipes and the bottom cover (3). A silk screen is provided at the connection point between the first outlet pipe (8-1) and the bottom cover (3). The mesh size of the silk screen is 200 mesh.

5. A method for culturing the widely distributed Cyclops fasciatus, characterized in that, The cultivation of *Daphnia magna* using the cultivation device described in claim 4 specifically includes the following steps: S1: Add water to the culture device (10) for the widely distributed Chinese water flea, add 1-3g of brown sugar, 1-3g of spirulina powder and 4-6mL of EM bacteria per liter of water, and add 100-200 Chinese water fleas; control the water temperature to 15-20℃ and the pH to 6-8.5, turn on the second light source (5-2) and the third light source (5-3), and cultivate for 5 days; S2: Change the water, add 3-5g of brown sugar, 4-6g of spirulina powder and 7-9mL of EM bacteria per liter of water, and incubate for 3 days; S3: Change the water again, add 4-6g of brown sugar, 7-9g of spirulina powder and 8-12mL of EM bacteria per liter of water, and culture until the density of Cyprinidaria fasciata reaches 800-1200 ind / L; S4: Turn on the first light source (5-1), turn off the second light source (5-2) and the third light source (5-3) for 5-8 minutes, then open the valve of the first outlet pipe (8-1) to release water. Widespread Cypriniformes smaller than 0.85mm accumulate in the lower part of the collection pipe (4), and widespread Cypriniformes larger than 0.85mm accumulate in the lower part of the cylinder (1). Then, output widespread Cypriniformes larger than 0.85mm through the second outlet pipe (8-2). S5: Add water again, adding 4-6g of brown sugar, 7-9g of spirulina powder and 8-12mL of EM bacteria per liter of water. Turn off the first light source (5-1), turn on the second light source (5-2) and the third light source (5-3), and continue culturing. Repeat step S4 when the density of the widely distributed Cyprinidaria reaches 800-1200 ind / L.

6. The method for culturing the widely distributed Cyprinidaria according to claim 5, characterized in that: In step S1, the amount of brown sugar is 2g, the amount of spirulina powder is 2g, the amount of EM bacteria is 5mL, the amount of Cyprinus fasciatus is 150, the water temperature is 18℃, and the pH is 7. In step S2, the amount of brown sugar is 4g, spirulina powder is 5g, and EM bacteria is 8mL; In step S3, the amount of brown sugar is 5g, spirulina powder is 8g, and EM bacteria is 10mL; the density is 1000 ind / L. In step S4, the first light source (5-1) is turned on, and the second light source (5-2) and the third light source (5-3) are turned off for 5 minutes. In step S5, the amount of brown sugar is 5g, spirulina powder is 8g, and EM bacteria is 10mL; the density of the widely distributed Cyclops is 1000 ind / L.

7. The application of the widely distributed Chinese water flea culture device according to claim 4 in the preparation of a biological control device for white spot disease in fish.

8. The application according to claim 7, characterized in that: Application of the widely distributed Chinese water flea culture device (10) in the preparation of a biological control device for white spot disease in longfin gudgeon.

9. The application according to claim 8, characterized in that: The effective density of Cynactus chinensis, widely distributed in the biological control device for white spot disease of the longfin gudgeon, is 450-550 ind / L.

10. The application according to claim 8, characterized in that: The biological control device for white spot disease in longfin gudgeon includes the widely distributed daphnia culture device (10) and a fish farming system. The fish farming system includes a farming pond (21), a microfilter (22), a return water pond (23), a circulation pump (24), a sterilizer (25), and a biological moving bed (26). The outlet of the biological moving bed (26) is divided into two pipelines, one of which connects to the inlet pipeline of the widely distributed daphnia culture device (10), and the other connects to the inlet of the farming pond (21). The widely distributed daphnia culture device (10) has... The second outlet pipe (8-2) is connected to the inlet of the breeding pond (21), and the first outlet pipe (8-1) of the widely distributed Chinese water flea culture device (10) is connected to the inlet of the microfilter (22); the outlet of the breeding pond (21) is connected to the inlet of the microfilter, the outlet of the microfilter is connected to the inlet of the return water tank (23), the outlet of the return water tank (23) is connected to the inlet of the circulation pump (24), the outlet of the circulation pump (24) is connected to the inlet of the sterilizer (25), and the outlet of the sterilizer (25) is connected to the inlet of the biological moving bed (26).

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