Method for preventing and treating ichthyophthiriasis of industrially cultured snakehead fry

Abstract

The invention discloses a method for preventing and treating ichthyophthiriasis of industrially cultured snakehead fries, which belongs to the technical field of snakehead culture and comprises the following steps: completely catching snakehead fries infected with ichthyophthiriasis in a culture pond, and transferring the snakehead fries into a biological bait culture pond for isolated culture; transferring the snakeheads subjected to isolated culture to a culture pond, and raising the salinity of the culture pond for culture; in the same period of culturing in the culture pond, the composite Chinese herbal medicine preparation is splashed into the culture pond to conduct soaking treatment on the snakeheads; after treatment is finished, in daily culture in a culture pond, a red-knees herb decoction water solution is splashed into the culture pond to consolidate the treatment effect of the snakehead and prevent the snakehead. Through the synergistic effect of sick fish isolation, salinity regulation and control and red-knees herb treatment, the survival rate and quality of fish culture are remarkably improved, the culture yield is increased, economic benefits are improved, ecological benefits are improved, and powerful support is provided for green development of factory fish culture.

Description

Technical Field

[0001] This invention relates to the field of snakehead aquaculture technology, specifically to a method for preventing and controlling Ichthyophthirius multifiliis disease in snakehead seedlings raised in industrialized farms. Background Technology

[0002] Ichthyophthirius multifiliis (white spot disease) is a common and serious parasitic disease in fish farming. When severely infected, the fish's skin and gills are covered with a layer of small white spots, hence the name "white spot disease." In factory aquaculture environments, due to the high stocking density and relatively enclosed water bodies, an outbreak of Ichthyophthirius multifiliis can spread rapidly, causing huge losses to fish farming.

[0003] The life cycle of *Ichthyophthirius multifiliis* mainly consists of four stages: trophozoite, adult, cyst, and predator. The parasitic stage on fish is primarily the trophozoite stage. Mature adults emerge from the epidermis, sink to the bottom, or attach to suspended matter. The cilia on the worm's surface disappear, and a gel-like substance is secreted to form a cyst. Under suitable water temperatures, the cyst undergoes multiple fissions to produce predator larvae. These predators swim freely in the water, find a fish, and then burrow under the epidermis of the gills, skin, or fins to develop into trophozoites.

[0004] Under suitable temperature and water conditions, Ichthyophthirius multifiliis reproduces and grows rapidly. Within 1 to 2 weeks, a few inconspicuous worms can form a large number of white spots, covering the gills, skin, and fins of fish. Most of the "white spots" on the fish's body surface are adult worms and cysts.

[0005] Currently, the prevention and control of Ichthyophthirius multifiliis disease faces many challenges. These mainly include: 1. Traditional chemical drugs can lead to drug resistance and do not align with the concept of green and environmentally friendly farming. While traditional chemical drug treatment can control the disease to some extent, drug residues can affect the quality of fish and may also disrupt the ecological balance of the aquaculture water. Long-term use can easily lead to drug resistance in Ichthyophthirius multifiliis. At the same time, frequent use of chemical drugs increases aquaculture costs and does not conform to the concept of green and environmentally friendly aquaculture. 2. In aquaculture, many traditional Chinese medicine prevention and treatment combinations have not been practically applied due to limitations in sales channels and cumbersome preparation processes. There are numerous patented traditional Chinese medicines for the prevention and treatment of Ichthyophthirius multifiliis. However, due to factors such as market sales channels, it is difficult for breeding enterprises to accurately purchase single varieties of Chinese medicinal materials. In addition, the formulations of some medicines are complex, making it difficult for breeding enterprises to prepare them. Since the commercialization of patented technologies takes time, only a very small number of patented formulas are mass-produced in factories, resulting in limited application.

[0006] 3. The application of technologies such as biological control is not yet mature. While biological control methods show promise, the technology is not yet mature enough for widespread application in actual production.

[0007] In actual aquaculture, mass mortality, slow growth, and quality decline in fish due to Ichthyophthirius multifiliis (white spot disease) are common occurrences, severely hindering the healthy development of the factory-scale fish farming industry. Currently, there are many patents reported for treating Ichthyophthirius multifiliis. Raising the water temperature to 28-30℃ can effectively prevent white spot disease, but this method is energy-intensive and costly, unsuitable for large-scale artificial aquaculture. Controlling the water flow rate in the aquaculture pond can reduce the parasitism rate of Ichthyophthirius multifiliis on the fish, thus achieving control of white spot disease, but this has the disadvantage of excessively high construction and investment costs. Using chemical drug preparations for the prevention and treatment of white spot disease can lead to drug resistance within the parasite population through repeated treatments, resulting in poor control effects. For example, patents CN110946984 A, CN 115845015 A, and CN 108721345 A report a drug and preparation method for treating freshwater Ichthyophthirius multifiliis. Due to the complex composition of the drug, it is difficult for general aquaculture enterprises to formulate it before large-scale factory production. Patent CN 110279792 A discloses a traditional Chinese medicine for treating Ichthyophthirius multifiliis (white spot disease). However, due to market sales channels and other issues, aquaculture enterprises find it difficult to accurately purchase single types of medicinal materials. Patent CN109400691B (An antimicrobial peptide for the prevention and treatment of Ichthyophthirius multifiliis) reports a new approach to treating Ichthyophthirius multifiliis, but this method requires a large amount of antimicrobial peptide, resulting in high treatment costs. Patent CN104784194B (Application of natamycin in killing Ichthyophthirius multifiliis and stimulating Cryptocaryon cynomolgus) reports the application of natamycin in the treatment of Ichthyophthirius multifiliis, but this drug has a certain impact on the environment and its application cost is also high, making it unsuitable for large-scale promotion. Patent CN107027668B (A method for preventing and treating Ichthyophthirius multifiliis in cage-cultured pomfret) reports a method for preventing and treating Ichthyophthirius multifiliis in pomfret, using freshwater stimulation of marine fish, which can be effective for treating Ichthyophthirius multifiliis in fish. However, this is a single preventive measure, and the sudden increase or decrease in salinity can cause certain irritation to the fish. To date, no environmentally friendly and effective method for treating Ichthyophthirius multifiliis has been reported.

[0008] Therefore, developing a method to prevent and control Ichthyophthirius multifiliis disease in farmed snakehead seedlings is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] In view of this, the present invention provides a method for preventing and controlling Ichthyophthirius multifiliis disease in farmed snakehead seedlings.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for preventing and controlling Ichthyophthirius multifiliis disease in farmed snakehead seedlings includes the following steps: (1) All snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding ponds were captured and transferred to biological feed culture ponds for isolated breeding; (2) Transfer the snakehead fish isolated and cultured in step (1) to the factory-style workshop culture pond, and raise the salinity of the factory-style workshop culture pond before culture; (3) During the same period of breeding in the factory workshop breeding pond in step (2), the compound Chinese herbal medicine preparation is sprinkled into the factory workshop breeding pond to soak the snakehead for treatment; (4) After the treatment, during the daily breeding in the breeding pond, the decoction of Polygonum hydropiper is sprinkled into the breeding pond in the factory workshop to consolidate the treatment effect and carry out prevention.

[0011] Furthermore, in step (1), all snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding pond are harvested and transferred to a biological feed culture pond for isolation and breeding for 7-10 days. The isolation and breeding ends when there are no symptoms on the body surface.

[0012] Furthermore, in step (2), the specific steps to increase the salinity of the aquaculture pond in the factory workshop are as follows: lower the water level of the aquaculture pond in the factory workshop, add sea salt crystals, and raise the salinity of the water in the aquaculture pond in the factory workshop to 4‰-6‰ and then raise it for 7-10 days; during the aquaculture period after the salinity is increased, add vitamin C and immune polysaccharides to the aquaculture water every day.

[0013] Furthermore, in step (2), the dissolved oxygen content is increased to maintain the dissolved oxygen content of the aquaculture pond water at 6-8 mg / L. The amount of vitamin C and immunopolysaccharide added is 2-3 g of vitamin C and 0.3-0.5 g of immunopolysaccharide per cubic meter of water, respectively.

[0014] Furthermore, the method is used for the control of small white worms in the industrialized seedling cultivation of snakehead fish.

[0015] Furthermore, in step (3), 10-20g of compound Chinese herbal medicine preparation is added per cubic meter of water.

[0016] Further, in step (3), the preparation method of the compound traditional Chinese medicine preparation includes the following steps: after pulverizing dried Polygonum hydropiper through a 60-80 mesh sieve, mix dried Polygonum hydropiper, fresh chili peppers and fresh ginger in a mass ratio of 1:1:1, add 5-10 times the amount of water and heat at 100℃ for 20-30 minutes to obtain a compound traditional Chinese medicine decoction solution; evenly sprinkle it into the factory breeding pond every 2-3 days and use it continuously for 15-20 days.

[0017] Furthermore, in step (4), the preparation method of the Polygonum hydropiper decoction includes the following steps: cut the Polygonum hydropiper into 1-3cm stem segments, add 5-10 times the amount of water, heat and decoct at 100℃ for 20-30 minutes to obtain the Polygonum hydropiper decoction; add 2-5g of Polygonum hydropiper decoction to each cubic meter of water, and sprinkle once every 5 days until the end of seedling cultivation.

[0018] The beneficial technical effects of this invention are as follows: Interrupting Transmission: By isolating and treating diseased fish, the transmission route of Ichthyophthirius multifiliis (white spot disease) to healthy fish populations is effectively blocked, reducing the risk of disease spread and ensuring the healthy growth of most fish. In the high-density farming environment of factory farms, diseased fish carry a large number of Ichthyophthirius multifiliis. If not isolated in time, the parasite will spread rapidly, endangering the entire fish population. This invention transfers diseased fish to a biological feed culture tank for isolated rearing, cutting off the transmission chain of Ichthyophthirius multifiliis in the factory farm, greatly reducing the chance of infection in healthy fish, and creating a safe growth environment for the fish population.

[0019] Ecological control: The biological feed culture pond contains a large number of plankton (such as rotifers, cladocerans, copepods, and other zooplankton), protozoa, and algae. These organisms compete with Ichthyophthirius multifiliis for resources (organic detritus, dissolved oxygen, and attachment space in the water) and predation pressure (some zooplankton can feed on free larvae of Ichthyophthirius multifiliis), directly inhibiting the survival of larvae, the efficiency of attachment to fish, and the hatching success rate of cysts. This ecologically breaks the cycle of "infection-reproduction-diffusion," achieving the effect of biological control.

[0020] Salinity suppression: The salinity of the aquaculture water is increased, taking advantage of the sensitivity of Ichthyophthirius multifiliis (white spot disease parasite) to salinity changes, while snakehead fry can tolerate high salinity, thus inhibiting the growth and reproduction of Ichthyophthirius multifiliis. The salinity is increased to 4‰-6‰ and maintained for 7-10 days. This suppresses Ichthyophthirius multifiliis while reducing stress on the fry, ensuring normal physiological functions of the fish. This precise salinity control method effectively inhibits the proliferation of Ichthyophthirius multifiliis without negatively impacting the health of the fish, ensuring the stability of the aquaculture process.

[0021] Advantages of Compound Traditional Chinese Medicine Preparations: The flavonoids and polysaccharides in the decoction of Polygonum hydropiper can effectively improve the immunity of fish. Flavonoids have antioxidant and anti-inflammatory effects, which can enhance the antioxidant defense system of fish, reduce the damage of free radicals to fish tissues, and thus improve the immunity of fish. Polysaccharides can activate immune cells such as macrophages and lymphocytes in the fish immune system, promote the proliferation and activity of immune cells, enhance the resistance of fish to pathogens, and reduce the incidence of Ichthyophthirius multifiliis disease from the source. Gingerol and gingerone in ginger and capsaicin in chili peppers are irritating and can act on the larvae (infectious ciliated larvae) and cyst stages of Ichthyophthirius multifiliis, destroying their cell membrane integrity, inhibiting ciliary movement, preventing larvae from attaching to the fish, or causing mature cysts on the surface of the fish to fall off, thereby interrupting the life cycle of Ichthyophthirius multifiliis (Ichthyophthirius multifiliis needs to rely on fish to parasitize in order to complete reproduction).

[0022] Enhanced Overall Benefits: A multi-pronged approach is used to achieve highly efficient and ecological control of Ichthyophthirius multifiliis (white spot disease) in factory-farmed aquaculture facilities. Through the synergistic effect of isolating diseased fish, controlling salinity, and treating with Polygonum hydropiper, the survival rate and quality of farmed fish are significantly improved, promoting the sustainable development of the factory-farmed aquaculture industry. This not only increases aquaculture yield and improves economic benefits but also avoids the drug residues and environmental pollution problems associated with traditional chemical treatments, thus enhancing ecological benefits and providing strong support for the green development of factory-farmed aquaculture. Attached Figure Description

[0023] Figure 1 A flowchart illustrating the combined control methods for Ichthyophthirius multifiliis in factory-scale aquaculture workshops.

[0024] Figure 2 This is a picture of the actual immunopolysaccharide raw material. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The immunopolysaccharide used in this invention was purchased from Shanxi Yikang Animal Pharmaceutical Co., Ltd., and its product name is Astragalus membranaceus crude extract immunopolysaccharide, a natural plant feed ingredient, with product standard number Q / 140802102002SYK131-2021.

[0027] Example 1 Methods for preventing and controlling Ichthyophthirius multifiliis disease in farmed snakehead seedlings include the following steps: (1) All snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding pond were caught and transferred to the biological feed culture pond for isolation and breeding for 10 days. The isolation and breeding were ended after the skin showed no symptoms. (2) Transfer the snakehead fish isolated and cultured in step (1) to the factory-style workshop culture pond, and raise the salinity of the factory-style workshop culture pond before culture. Lower the water level of the factory-style workshop culture pond, add sea salt crystals, add 6 kg of sea salt crystals per cubic meter of water, raise the salinity of the water in the factory-style workshop culture pond to 6‰ and culture for 10 days. During the culture period after the salinity is raised, add vitamin C and immunopolysaccharide to the culture water every day. The amount of vitamin C and immunopolysaccharide added is 2g of vitamin C and 0.5g of immunopolysaccharide per cubic meter of water, respectively, to increase the dissolved oxygen and maintain the dissolved oxygen of the culture pond water at 6.5mg / L. (3) During the same period of breeding in the factory workshop breeding pond in step (2), the compound Chinese herbal medicine preparation is sprinkled into the factory workshop breeding pond to soak and treat the snakehead. 15g of compound Chinese herbal medicine preparation is added per cubic meter of water. The preparation method of the compound Chinese herbal medicine preparation includes the following steps: after crushing the dried Polygonum hydropiper through an 80-mesh sieve, the dried Polygonum hydropiper, fresh chili pepper and fresh ginger are mixed in a mass ratio of 1:1:1, 10 times the amount of water is added and heated at 100℃ for 30 minutes to obtain a compound Chinese herbal medicine decoction solution; it is evenly sprinkled into the factory breeding pond every 3 days and used continuously for 18 days. (4) After the treatment, during the daily breeding in the breeding pond, the decoction of Polygonum hydropiper is sprinkled into the breeding pond in the factory workshop to consolidate the treatment effect and prevent the snakehead. The preparation method of the decoction of Polygonum hydropiper includes the following steps: cut Polygonum hydropiper into 1-3cm stem segments, add 10 times the amount of water and heat at 100℃ for 30 minutes to obtain the decoction of Polygonum hydropiper; sprinkle 5 grams of decoction of Polygonum hydropiper per cubic meter of water, once every 5 days, until the end of the seedling breeding.

[0028] Example 2 Methods for preventing and controlling Ichthyophthirius multifiliis disease in farmed snakehead seedlings include the following steps: (1) All snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding pond were caught and transferred to the biological feed culture pond for isolation and breeding for 8 days. The isolation and breeding were ended after the skin showed no symptoms. (2) Transfer the snakehead fish isolated and cultured in step (1) to the factory-style workshop culture pond, and raise the salinity of the factory-style workshop culture pond before culture. Lower the water level of the factory-style workshop culture pond, add sea salt crystals, add 5 kg of sea salt crystals per cubic meter of water, raise the salinity of the water in the factory-style workshop culture pond to 5‰ and culture for 8 days. During the culture period after the salinity is raised, add vitamin C and immune polysaccharides to the culture water every day. The amount of vitamin C and immune polysaccharides added is 3g of vitamin C and 0.3g of immune polysaccharides per cubic meter of water, respectively, to increase the dissolved oxygen and maintain the dissolved oxygen in the culture pond water at 7mg / L. (3) During the same period of breeding in the factory workshop breeding pond in step (2), the compound Chinese herbal medicine preparation is sprinkled into the factory workshop breeding pond to soak and treat the snakehead. 10g of compound Chinese herbal medicine preparation is added per cubic meter of water. The preparation method of the compound Chinese herbal medicine preparation includes the following steps: after crushing the dried Polygonum hydropiper through an 80-mesh sieve, the dried Polygonum hydropiper, fresh chili pepper and fresh ginger are mixed in a mass ratio of 1:1:1, 8 times the amount of water is added and heated at 100℃ for 20 minutes to obtain a compound Chinese herbal medicine decoction solution; it is evenly sprinkled into the factory breeding pond every 2 days and used continuously for 15 days. (4) After the treatment, during the daily breeding in the breeding pond, the decoction of Polygonum hydropiper is sprinkled into the breeding pond in the factory workshop to consolidate the treatment effect and prevent the snakehead. The preparation method of the decoction of Polygonum hydropiper includes the following steps: cut Polygonum hydropiper into 1-3cm stem segments, add 8 times the amount of water and heat at 100℃ for 20 minutes to obtain the decoction of Polygonum hydropiper; sprinkle 3 grams of decoction of Polygonum hydropiper per cubic meter of water, once every 5 days, until the end of the seedling breeding.

[0029] Example 3 Methods for preventing and controlling Ichthyophthirius multifiliis disease in farmed snakehead seedlings include the following steps: (1) All snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding pond were caught and transferred to the biological feed culture pond for isolation and breeding for 7 days. The isolation and breeding were ended after the skin showed no symptoms. (2) Transfer the snakehead fish isolated and cultured in step (1) to the factory-style workshop culture pond, and raise the salinity of the factory-style workshop culture pond before culture. Lower the water level of the factory-style workshop culture pond, add sea salt crystals, add 6 kg of sea salt crystals per cubic meter of water, raise the salinity of the water in the factory-style workshop culture pond to 6‰ and culture for 7 days. During the culture period after the salinity is raised, add vitamin C and immune polysaccharides to the culture water every day. The amount of vitamin C and immune polysaccharides added is 2g of vitamin C and 0.5g of immune polysaccharides per cubic meter of water, respectively, to increase the dissolved oxygen and maintain the dissolved oxygen in the culture pond water at 8mg / L. (3) During the same period of breeding in the factory workshop breeding pond in step (2), the compound Chinese herbal medicine preparation is sprinkled into the factory workshop breeding pond to soak and treat the snakehead. 20g of compound Chinese herbal medicine preparation is added per cubic meter of water. The preparation method of the compound Chinese herbal medicine preparation includes the following steps: after crushing the dried Polygonum hydropiper through a 60-mesh sieve, the dried Polygonum hydropiper, fresh chili and fresh ginger are mixed in a mass ratio of 1:1:1, 6 times the amount of water is added and heated at 100℃ for 25 minutes to obtain the compound Chinese herbal medicine decoction solution; it is evenly sprinkled into the factory breeding pond every 3 days and used continuously for 20 days. (4) After the treatment, during the daily breeding in the breeding pond, the decoction of Polygonum hydropiper is sprinkled into the breeding pond in the factory workshop to consolidate the treatment effect and prevent the snakehead. The preparation method of the decoction of Polygonum hydropiper includes the following steps: cut Polygonum hydropiper into 1-3cm stem segments, add 6 times the amount of water and heat at 100℃ for 25 minutes to obtain the decoction of Polygonum hydropiper; sprinkle 4 grams of decoction of Polygonum hydropiper per cubic meter of water, once every 5 days, until the end of the seedling breeding.

[0030] Experimental Example 1 In August 2025, during the cultivation of snakehead fry at the West Suburb Base of the Shandong Freshwater Fisheries Research Institute, aquaculture personnel discovered Ichthyophthirius multifiliis (white spot disease) during an inspection. Eight identical culture tanks, each with a volume of 4 m³, were selected. Snakehead fry of 2-3 g / fish were stocked in each tank with 500 fry. Ponds 1 and 2 served as the experimental group, employing the ecological control method described in Example 1 of this invention. Ponds 3-8 served as the control group, receiving treatment using traditional chemical drugs, salinity enhancement, and Polygonum hydropiper application, respectively.

[0031] Experimental group 1-2 barrels: The operation was carried out according to the method in Example 1.

[0032] Control group tanks 3-4: After the discovery of Ichthyophthirius multifiliis disease, treatment was carried out with a mixture of copper sulfate and ferrous sulfate (5:2), applied to the entire pond at a dosage of 0.7g per cubic meter of water, once every 3 days, for a total of 3 times.

[0033] Control group tanks 5-6: After the discovery of Ichthyophthirius multifiliis disease, no isolation of the biological feed culture pond or treatment with compound Chinese herbal medicine was carried out. Only the salinity was increased. Other steps and parameters were the same as in Example 1.

[0034] Control group tanks 7-8: After the discovery of Ichthyophthirius multifiliis disease, no biological feed culture pond or salinity enhancement culture was carried out. Only compound Chinese herbal medicine preparation was sprayed for treatment. Other steps and parameters were the same as in Example 1.

[0035] Control group (buckets 9-10): No treatment was given after Ichthyophthirius multifiliis was detected.

[0036] The total mortality rate in each culture pond was observed and recorded regularly within one month after treatment. The results are shown in Table 1 below: Table 1

[0037] As shown in Table 1, the experimental groups using the ecological control method of this invention were significantly better than the other control groups and the blank control group.

[0038] This invention addresses the characteristics of Ichthyophthirius multifiliis disease in factory aquaculture workshops by comprehensively utilizing various ecological prevention and control methods to create a favorable environment for fish growth, enhance fish immunity, and effectively control the occurrence and spread of Ichthyophthirius multifiliis disease.

[0039] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings, characterized in that, Includes the following steps: (1) All snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding ponds were captured and transferred to biological feed culture ponds for isolated breeding; (2) Transfer the snakehead fish isolated and cultured in step (1) to the factory-style workshop culture pond, and raise the salinity of the factory-style workshop culture pond before culture; (3) During the same period of breeding in the factory workshop breeding pond in step (2), the compound Chinese herbal medicine preparation is sprinkled into the factory workshop breeding pond to soak the snakehead for treatment; (4) After the treatment, during the daily breeding in the breeding pond, the decoction of Polygonum hydropiper is sprinkled into the breeding pond in the factory workshop to consolidate the treatment effect and carry out prevention.

2. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 1, characterized in that, In step (1), all snakehead seedlings infected with Ichthyophthirius multifiliis in the factory workshop breeding pond are harvested and transferred to a biological feed culture pond for isolation and breeding for 7-10 days. The isolation and breeding ends when there are no symptoms on the body surface.

3. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 1, characterized in that, In step (2), the specific steps to increase the salinity of the factory workshop aquaculture pond are as follows: lower the water level of the factory workshop aquaculture pond, add sea salt crystals, increase the salinity of the water in the factory workshop aquaculture pond to 4‰-6‰ and then aquaculture for 7-10 days; during the aquaculture period after the salinity is increased, add vitamin C and immune polysaccharides to the aquaculture water every day.

4. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 3, characterized in that, In step (2), the dissolved oxygen content is increased to maintain the dissolved oxygen content of the aquaculture pond water at 6-8 mg / L. The amount of vitamin C and immunopolysaccharide added is 2-3g of vitamin C and 0.3-0.5g of immunopolysaccharide per cubic meter of water, respectively.

5. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 3, characterized in that, The method described above is used for the control of small white worms in the industrialized seedling cultivation of snakehead fish.

6. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 1, characterized in that, In step (3), 10-20g of compound Chinese herbal medicine preparation is added per cubic meter of water.

7. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 6, characterized in that, In step (3), the preparation method of the compound traditional Chinese medicine preparation includes the following steps: after pulverizing dried Polygonum hydropiper through a 60-80 mesh sieve, mix dried Polygonum hydropiper, fresh chili pepper and fresh ginger in a mass ratio of 1:1:1, add 5-10 times the amount of water and heat at 100℃ for 20-30 minutes to obtain a compound traditional Chinese medicine decoction solution; evenly sprinkle it into the factory breeding pond every 2-3 days and use it continuously for 15-20 days.

8. The method for preventing and controlling Ichthyophthirius multifiliis disease in factory-cultured snakehead seedlings according to claim 1, characterized in that, In step (4), the preparation method of the decoction of Polygonum hydropiper includes the following steps: cut Polygonum hydropiper into 1-3cm stem segments, add 5-10 times the amount of water, heat and decoct at 100℃ for 20-30 minutes to obtain the decoction of Polygonum hydropiper; add 2-5 grams of Polygonum hydropiper per cubic meter of water, and sprinkle once every 5 days until the end of seedling cultivation.

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