A product for preventing and treating Ichthyophthirius spp. disease in longnose catfish fry

Abstract

The invention relates to the technical field of aquaculture methods, and specifically to a culture method for preventing and treating Ichthyophthirius spp. in long-nosed catfish fry. The technical scheme adopts a first system and a second system for sequential cyclic treatment, and finally adopts a third system for treatment, so as to achieve the prevention and treatment of Ichthyophthirius spp. The three systems are all subjected to temperature-raising treatment, and the first system contains sodium chloride and formaldehyde, which promotes the rapid shedding of the worm body and inhibits the larvae from stopping development; the second system contains povidone-iodine, which can prevent surface infection; the third system consolidates the treatment effect; and unhatched cysts and dead worm bodies are discharged by changing water during the treatment process. Physical heating measures are taken to reduce the osmotic stress of salinity on freshwater fish. The drugs used are all easily metabolized, free of heavy metal ions, and have ideal ecological safety and food safety. The technical scheme can solve the technical problem of the lack of a safe and effective culture method for preventing and treating Ichthyophthirius spp. in the prior art, and has an ideal prospect for promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of aquaculture methods, and in particular to a culture method for preventing and treating Ichthyophthirius gracilis disease in longnose catfish fry. Background Art

[0002] Ichthyophthirius multifida ( Ichthyophthirius multifiliis Ichthyophthirius (Ichthyophthirius occidentalis, hereinafter referred to as Ichthyophthirius occidentalis) is a common freshwater fish parasite, commonly known as "white spot disease". This parasite mainly affects freshwater fish, including ornamental fish and farmed fish, such as long-snout catfish. The main symptoms of freshwater fish such as long-snout catfish infected with Ichthyophthirius occidentalis are: white spots appear on the body surface, which is the most typical symptom. The white spots are actually vesicles formed by Ichthyophthirius occidentalis on the fish's body surface; changes in fish behavior: infected fish may rub their bodies frequently in an attempt to remove parasites from their bodies, and may also show symptoms such as restlessness, slow swimming, and loss of appetite; damage to the gills: in severe cases, Ichthyophthirius occidentalis will also invade the fish's gills, causing difficulty breathing. Ichthyophthirius occidentalis is difficult to treat mainly because it is difficult to observe in the early stages of the disease. Often, when obvious cysts are observed, the peak of mortality has already begun. Ichthyophthirius occidentalis has a special life history. The worm body parasitizes the fish body and is difficult to fall off. After falling off, it forms cysts and then reproduces larvae, which then parasitize the fish body. This process not only absorbs nutrients from the fish body, but also causes damage to the fish body, which is the reason for the high mortality rate of Ichthyophthirius occidentalis.

[0003] In the past, the prevention and control of Ichthyophthirius was mainly carried out through a combination of physical and drug methods. The physical method is mainly through heating, and the drug is mainly soaked in mercuric nitrite or copper sulfate solution. Mercury nitrite has been listed as a drug prohibited for use in aquaculture due to drug residues. Now it is found that soaking in copper sulfate cannot cure Ichthyophthirius. Copper sulfate will promote the shedding of Ichthyophthirius cysts, but after shedding, it will accelerate reproduction, which is counterproductive. Previously, high-salinity (salinity>15) water bodies were used to treat ornamental fish (goldfish, koi) with formaldehyde, potassium permanganate, copper sulfate and other drugs to treat Ichthyophthirius. However, this method may cause excessive heavy metal residues in the treatment of Ichthyophthirius in edible fish, and the osmotic stress of this method is too great, and it is not universally applicable to freshwater scaleless fish. In addition, the tolerance of scaleless fish and scaled fish and fish of different sizes to drugs parasitized by Ichthyophthirius is very different, and the dosage is not easy to control. Too high drug concentration leads to fish poisoning, and too low drug concentration leads to poor control effect. Farmers also use some folk remedies to treat Ichthyophthirius, such as boiling chili peppers and ginger in water and then pouring it throughout the pond, but the treatment effect is not ideal.

[0004] Longnose catfish (scientific name: Long-nosed leucocephalus), also known as Jiangtuan, catfish, and fathead fish in some areas of southern China. It belongs to the order Siluriformes, the family Catfish, and is a freshwater scaleless fish. Longnose catfish not only has a certain economic value and is loved by people as an edible fish, but is also used as an ornamental fish in some places. In addition, because they are sensitive to changes in water quality, they are sometimes used to monitor the quality of the water environment. Longnose catfish fry are extremely susceptible to Ichthyophthirius microtypingis. Once an outbreak occurs, the mortality rate is almost over 90%. As a scaleless fish, longnose catfish are more sensitive to drugs. Therefore, a safe and effective breeding method and breeding system for longnose catfish fry with Ichthyophthirius microtypingis is needed. Summary of the invention

[0005] The object of the present invention is to provide a breeding method for preventing and treating Ichthyophthirius scoparia, so as to solve the technical problem that there is a lack of a safe and effective breeding method for preventing and treating Ichthyophthirius scoparia in the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A breeding method for preventing and treating Ichthyophthirius sphaerocephalus comprises the following steps performed in sequence:

[0008] S1: Drug treatment step: including sequential and cyclic pathogen shedding and inactivation steps and buffer culture steps;

[0009] Pathogen shedding and inactivation steps: Cultivate the long-snout catfish in a water body that has been heated and contains sodium chloride, then add formaldehyde, and after drug treatment, replace the water body with fresh water;

[0010] Buffered culture step: culturing the long-snout catfish in fresh water until the next day, with or without the addition of povidone-iodine to the fresh water; then repeating the pathogen shedding and inactivation steps;

[0011] S2: Post-processing step: Cultivate the long-snout catfish in a temperature-elevated environment for one week.

[0012] Further, in S1, the index parameters of the water body are: final concentration of 3-5‰ sodium chloride, 26-28°C, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L;

[0013] The final concentration of formaldehyde is 90-120 ppm; the drug treatment duration is 30-40 minutes.

[0014] Furthermore, in S1, the final concentration of povidone-iodine was 0.5-0.75 ml / m 3; The frequency of the drug treatment step is once a day, lasting for 3-14 days; the frequency of using povidone-iodine is once every 1-2 days; in S2, the environmental temperature for culturing long-snout catfish is 26-28℃.

[0015] Furthermore, before S1, the Ichthyophthirius infection of long-snout catfish was isolated and identified: the granular white spots on the fish body surface and gills were examined microscopically, which showed that the white spots were round cysts with crescent-shaped worm bodies in them. Based on the cyst characteristics, it was confirmed to be Ichthyophthirius infection.

[0016] The technical solution also provides a system for preventing and treating Ichthyophthirius spp. in long-snout catfish, characterized in that it comprises a first system and a second system for culturing long-snout catfish sequentially and cyclically;

[0017] The first system includes a water body at 26-28°C, containing 3-5‰ sodium chloride and 90-120ppm formaldehyde, with 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L;

[0018] The second system includes water containing 3-5‰ sodium chloride at 26-28°C, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L, and a final concentration of 0.5-0.75ml / m is added or not added to the second system 3 of povidone-iodine.

[0019] Further, the second system is used to culture the long-snout catfish treated by the first system; the first system and the second system are used once a day and for 3-14 days;

[0020] The first system is used to culture long-snout catfish for 30-40 minutes; povidone-iodine is added to the second system once every 1-2 days.

[0021] Furthermore, it also includes a third system; the third system includes water with a temperature of 26-28°C, 5 mg / L<water dissolved oxygen<9 mg / L, 0 mg / L<ammonia nitrogen<0.2 mg / L and 0 mg / L<nitrite<0.1 mg / L, containing 3-5‰ sodium chloride; the third system is used to culture the longnose catfish for one week after the longnose catfish is cyclically treated in the first system and the second system.

[0022] Furthermore, water used for water replacement or water replenishment of the first system, the second system and the third system is stored in a water reservoir; the water reservoir is first soaked with an oxalic acid solution and then cleaned; after the water is stored, chlorine dioxide is used for disinfection, and then aeration is used to remove residual chlorine.

[0023] Further, the first system is a water body containing 5‰ sodium chloride and 100ppm formaldehyde at 28°C, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L;

[0024] The second system is a water body containing 5‰ sodium chloride, 28°C, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L;

[0025] The first system is used to treat sick long-snout catfish for 40 minutes every day from the first to the fifth day, and the second system is used to treat sick long-snout catfish after the first system treatment is completed; the second system is added with 0.5-0.75 ml / m 3 of povidone-iodine.

[0026] Furthermore, the third system is a water body containing 3‰ sodium chloride at 28°C, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L.

[0027] The technical principle of this technical solution is:

[0028] After the pathogen was isolated, cultured and identified as Ichthyophthirius spp., the treatment effect of Ichthyophthirius spp. was improved by heating, adding salt, soaking in formaldehyde, changing water, soaking in povidone iodine and other operations. Through drug treatment, Ichthyophthirius spp. fell off the fish body to form cysts, which hatched into larvae. The larvae must be killed at the same time as the worm body fell off. Formaldehyde can cause the worm body to fall off quickly to form cysts. The larvae hatched from the cysts are very sensitive to temperature and salinity. When the water temperature is 26-28℃, the Ichthyophthirius larvae stop developing, and the larvae die above 28℃. The water body maintains a salinity of 3-5‰ (especially 5‰) for better results. After the worm body falls off, it will cause damage to the fish body surface. Povidone iodine is used to prevent surface infection and inhibit Ichthyophthirius spp. at the same time. During the treatment process, unhatched cysts and dead worm bodies are discharged by changing water. This method has a good effect on young fish for 3-5 consecutive days, and can be used for adult fish for two weeks.

[0029] In addition, this technical solution uses formaldehyde and povidone-iodine to treat infected long-snout catfish. After the first system (containing formaldehyde) is treated, the second system (containing povidone-iodine) is used for treatment, which improves the effect of the treatment system of this solution on inhibiting Ichthyophthirius. In addition, after the first and second systems are treated alternately, the third system is added for treatment to further strengthen and consolidate the treatment effect. The treatment method of the first system of this solution also has a relatively large impact on the treatment effect. The treatment time of the first system is 40 minutes each time and lasts for 5 days, and its effect is most ideal.

[0030] The beneficial effects of this technical solution are:

[0031] (1) This method adopts physical heating measures to reduce the osmotic stress of salinity on freshwater fish. In addition, the drugs used are easily metabolized, do not contain heavy metal ions, and will not accumulate in aquatic organisms to cause heavy metal pollution, thereby improving ecological safety and food safety.

[0032] (2) Compared with mercuric nitrite, the drug used in this method is metabolized quickly and leaves no residue. Formaldehyde is volatile and evaporates quickly after use, making it highly safe. Povidone-iodine is a commonly used disinfectant and sterilizer that is less irritating to fish and leaves no residue in the body.

[0033] (3) Low cost, more suitable for large-scale aquaculture. The drugs used are commonly used drugs in aquaculture, with low price, wide source and quick effect.

[0034] (4) Provide methods for the isolation, cultivation and identification of Ichthyophthirius. Ichthyophthirius is a common parasitic disease that is difficult to observe in fish fry in the early stages of the disease. Therefore, a reasonable Ichthyophthirius detection program is needed. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following examples and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used can be obtained from commercial sources.

[0036] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below.

[0037] The term "salinity" refers to the concentration of dissolved salts (mainly sodium chloride, i.e. table salt) in water. A water salinity of 3 means a salt content of 3‰, or 3 grams of salt per liter of water.

[0038] The term "dissolved oxygen (DO)" refers to the amount of oxygen dissolved in water.

[0039] The term "ammonia-N" is an important indicator of water quality. Especially in aquaculture, the concentration of ammonia-N has a direct impact on the health and survival of fish. Ammonia-N is a kind of ammonia (NH 3 ) and ammonium ions (NH 4 ⁺) in the form of nitrogen compounds. In water, these two forms can be converted into each other, and the rate of conversion depends on the pH value and temperature of the water.

[0040] The term "Trophont": It is round or oval in shape, about 0.5-1.0 mm in diameter, and visible to the naked eye. Trophozoites form white vesicles on the body surface and gills of fish.

[0041] The term "Tomont" refers to the mature trophozoites that fall off the fish and attach to the bottom of the aquarium or other surfaces to form a cyst.

[0042] Term "Sporozoite": The cyst divides into multiple sporozoites under favorable conditions, which swim and seek out new host fish.

[0043] Terminology "Life cycle of Ichthyophthirius spp." Trophozoite stage: Ichthyophthirius spp. parasitizes on the body and gills of fish, absorbs nutrients, and gradually grows. The trophozoites form white vesicles on the fish body, which are visible to the naked eye.

[0044] Cyst stage: When the trophozoite matures, it will fall off the fish body and form a cyst, which is attached to the bottom of the aquarium or other surfaces. The cyst usually splits into multiple sporozoites within 24-48 hours at a water temperature of 15-25℃.

[0045] Sporozoite stage: Sporozoites are released from the cysts, swim and seek out new host fish. Sporozoites swim in the water for a limited time, usually 2-3 days, and die if they cannot find a host.

[0046] The following is further described in detail through specific implementation methods:

[0047] Example 1: Treatment of young longnose catfish

[0048] There are four 2m×1m×1m square breeding boxes in a breeding workshop, with a total of more than 10,000 one-month-old long-snout catfish fry. During the breeding process, the water temperature was 20.5℃, the dissolved oxygen was >5 mg / L, the ammonia nitrogen was <0.2 mg / L, and the nitrite was <0.1 mg / L. After 15 days of breeding, a small number of fry were found to have died. Samples were taken from the mucus and gills of the sick fish. The gills and body mucus were scraped with a glass slide, rinsed with clean water, and impurities were removed. The cysts were observed under an optical microscope, and the cysts were transferred to a culture dish with a pipette, clean water was added, and cultured in the dark. After 4 days, the larvae were observed to hatch, and the larvae were transferred to a plastic bucket containing 150L of fresh water for culture. Ten long-snout catfish were placed in the bucket, each weighing about 20g. After 3 days of culture at a water temperature of 20.5℃, granular white spots were observed on the fish body and gills. Microscopic examination showed that the white spots were round cysts with crescent-shaped worm bodies in them. Based on the characteristics of the cysts, it was diagnosed as Ichthyophthirius spp. and it was speculated that the outbreak of Ichthyophthirius spp. was caused by low water temperature and insufficient light, and treatment measures were taken immediately.

[0049] (1) Preparation of aquaculture water: Prepare a water reservoir of appropriate size, soak it in 3% oxalic acid solution (optional range 3-10%), and then clean the pool. After the water is stored, disinfect it with 0.5 ppm chlorine dioxide (optional range 0.2-0.6ppm) and aerate it for 24 hours (optional range 12-24 hours) to remove residual chlorine. Use a heating device to raise the water temperature to 28°C (optional range 26-28°C), and add sodium chloride to make the water salinity reach 3-5‰. Maintain: 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L, 0mg / L<nitrite<0.1mg / L. In the subsequent treatment process, water changes and water replenishment operations all use the treated water in the water reservoir.

[0050] (2) Regulation of the water body of the diseased pool: isolate the diseased pool, and the nets, buckets and other equipment used cannot be mixed with other pools to avoid cross-contamination between pools. Use heating equipment to slowly raise the water temperature to 28°C (optional range 26-28°C), and control 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L, 0mg / L<nitrite<0.1mg / L. After the water temperature and various water body indicators are stable, carry out drug treatment.

[0051] (3) Drug treatment method: Add sodium chloride to the pond to make the salinity reach 5‰ (optional range 3-5‰). In actual use, it was found that sodium chloride solid can be added directly, and the fish have no stress response to this salinity change. Then spray the whole pond with formaldehyde, and the final concentration of the drug is 100ppm (optional range 90-120ppm). The above two drugs can be used at the same time. After soaking for 35min (optional range 30-40min), drain the water and then add the above-mentioned treated water (water containing 5‰ sodium chloride at 28℃, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L). Sodium chloride can adjust the osmotic pressure of the water body, reduce the adhesion of the Ichthyophthirius spp. on the fish surface, and make it easier to fall off. Formaldehyde has a strong bactericidal and insecticidal effect, which can kill the free-living stage and parasitic stage of the Ichthyophthirius spp., and can also inhibit the spore formation of the Ichthyophthirius spp. and reduce its reproductive capacity. Drug treatment is carried out at relatively high temperatures. Increased water temperature accelerates the life cycle of Ichthyophthirius. At a water temperature of 25-30°C, the entire life cycle of Ichthyophthirius is about 3-5 days. This can shorten the treatment cycle because the life cycle of the parasite becomes shorter, reducing the time it spends on the fish body. Increasing water temperature can enhance the effect of certain therapeutic drugs, such as salt and formaldehyde. At high temperatures, the penetration and effectiveness of drugs will be enhanced to a certain extent.

[0052] After the water is changed, add povidone iodine at a dosage of 0.5 ml / m 3 (The dosage can be increased to 0.5-0.75 ml / m depending on the damage to the fish body. 3 ), disinfect the fish surface damage. Povidone-iodine has a strong bactericidal and insecticidal effect, which can kill Ichthyophthirius and other parasites in the water, inhibit the spore formation of Ichthyophthirius, reduce its reproductive capacity, and reduce the inflammatory response on the fish surface and promote wound healing. After completing the sodium chloride and formaldehyde treatment on the same day, the fry were cultured in water containing povidone-iodine. The sodium chloride and formaldehyde treatment process was repeated the next day, that is, the long-snout catfish was treated with water containing formaldehyde and sodium chloride, soaked for 35 minutes, and then replaced with treated water.

[0053] The frequency of use of sodium chloride and formaldehyde is once a day for 3-5 days, but povidone iodine needs to be used every 1-2 days. When povidone iodine is not needed, just replace the water containing sodium chloride and formaldehyde with treated water without povidone iodine. The feeding amount can be reduced during the treatment process. In actual operation, there is a big difference in the dosage of scaled fish and scaleless fish. Generally speaking, the dosage of scaled fish can be appropriately increased to achieve better therapeutic effects.

[0054] (4) Post-treatment treatment: After the treatment, the water should be kept warm for one week (28℃, the optional range is 26-28℃; the water contains 3‰ sodium chloride, the optional range is 3-5‰; 5mg / L< dissolved oxygen in the water<9 mg / L, 0 mg / L< ammonia nitrogen<0.2mg / L and 0 mg / L< nitrite<0.1 mg / L) to prevent secondary infection of Ichthyophthirius. For fish that are easily infected with Ichthyophthirius, such as copper fish, they can be kept in water with a salinity of 3‰ for a long time, which has a good effect on the prevention and treatment of Ichthyophthirius.

[0055] This technical solution treats the aforementioned infected longnose catfish fry, and the administration time of sodium chloride and formaldehyde is 5 days, once a day, and povidone iodine is added for treatment on the first / third / fifth day. After the drug treatment is completed, the heating is continued for one week to stabilize the treatment effect. Finally, the fry are sampled and observed under a microscope. It is found that there are no cysts on the body surface and gills, and the survival rate of the fry is more than 90%. The survival rate refers to the percentage of the number of animals after drug treatment to the number of animals before treatment. The number of animals is counted once before drug treatment and once after the drug treatment is stable.

[0056] Example 2: Treatment of adult longnose catfish

[0057] In a breeding workshop in Qianwei County, Leshan City, more than 500 long-snouted catfish (weighing about 50g) were raised in two circular pools (2m in diameter and 1.5m in depth). On August 5, 2024, white granular parasites were found on the surface of the long-snouted catfish. Samples of the body mucus and gills were taken for microscopic examination, and they were finally diagnosed with Ichthyophthirius acutiloba. The treatment scheme of Example 1 was adopted for the infected long-snouted catfish. However, since the long-snouted catfish was larger this time, the treatment time was longer, reaching two weeks. That is: sodium chloride and formaldehyde were applied daily for two weeks; povidone-iodine was applied every other day. After the treatment, the survival rate of this batch of long-snouted catfish was greater than 95%, and no cysts were found on its body surface and gills by microscopic examination. The treatment achieved good results.

[0058] Example 3: Exploration of process conditions

[0059] In this example, an experimental animal model was established by artificially infecting Ichthyophthirius spp. pathogens, and related breeding methods were studied. The method for establishing the experimental animal model was carried out with reference to the literature "Yu YY, Kong W, Yin YX, Dong F, Huang ZY, Yin GM, et al. (2018) Mucosal immunoglobulins protect theolfactory organ of teleost fish against parasitic infection. PLoS Pathog 14(11)". The general process is as follows: After the heavily infected longnose catfish is anesthetized, it is placed in a container filled with water to allow the trophozoites and cysts to fall off the fish body. The trophozoites and cysts are placed in water at 15°C for 24 hours to promote the formation of cysts and the subsequent release of sporozoites, which are used to infect experimental animals. The long-snout catfish was exposed to water with about 5,000 sporozoites / L for 3 hours, and then transferred to a breeding box containing ordinary new water (water temperature 20.5℃, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2 mg / L, 0mg / L<nitrite<0.1 mg / L). Observe whether some experimental animals begin to have white spots on their body surface or gills. Once white spots appear, it means that the experimental animals are infected with Ichthyophthirius spp. and the model is successful. The animal model with successful modeling is used to carry out the treatment process.

[0060] The experimental groups were as follows: each group contained 30 longnose catfish fry, each weighing about 20 g.

[0061] Untreated group: No drug treatment was given to the experimental animals. The fish were only cultured in a breeding box with a water temperature of 20.5℃, 5mg / L<dissolved oxygen in the water<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L, and 0mg / L<nitrite<0.1mg / L until the end of the experiment, and the survival rate was calculated. During the culture process, the water was changed regularly in the same way as in treatment group 1, but no drugs such as sodium chloride, formaldehyde and povidone iodine were added, and the temperature was not raised.

[0062] Treatment Group 1: Refer to Example 1. First, use the first system to culture the fry for 40 minutes. The parameters of the first system are: final concentration of 5‰ sodium chloride and final concentration of 100ppm formaldehyde, water temperature of 28°C, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L. Then, replace with fresh water, and form a second system to culture the fry. The parameters of the second system are: 5‰ sodium chloride, water temperature of 28°C, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L. When the second system is used for the first time, 0.5ml / m 3 Povidone iodine is applied every other day. The second system is used to culture the fry until the next time (the second day) it is replaced by the first system. That is, on the first day, the fry are treated with the first system for 40 minutes, and then the first system is replaced with the second system, and the fry are treated for about 23 hours and 20 minutes (in actual operation, the time varies, but try to replace the first system and the second system, or the second system and the first system at the same time); then the second system is replaced with the first system, and so on. The fry are treated in a cycle according to the above sequence, and the first system is used for treatment once a day for a total of 5 days, and povidone iodine is added to the second system on the first day / third day / fifth day for treatment. After the end, the fry are cultured in the third system for one week. The parameter conditions of the third system are: 3‰ sodium chloride, 28℃, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L. Before drug treatment and after the third system treatment, the number of surviving fry was counted and the survival rate was calculated, and it was observed whether cysts were still present on the body surface and gills after the drug treatment process (after the third system treatment).

[0063] Treatment group 2: This treatment group is basically the same as treatment group 1, with the difference that the conditions of the third system of this scheme are: 20.5℃, 3‰ sodium chloride, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L, 0mg / L<nitrite<0.1mg / L breeding box, that is, the temperature of the third system is lowered.

[0064] Treatment group 3: The procedure of this treatment group is basically the same as that of treatment group 1, except that:

[0065] The parameters of the first system are: sodium chloride with a final concentration of 5‰, formaldehyde with a final concentration of 100ppm, and a final concentration of 0.5ml / m 3of povidone iodine, water temperature 28°C, 5mg / L<dissolved oxygen in water<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L.

[0066] No povidone-iodine was added to the second system.

[0067] Treatment group 4: This treatment group included multiple groups (30 longnose catfish fry in each group) and explored the concentration conditions of povidone-iodine. The experimental process was basically the same as that of treatment group 1, except that the concentration conditions of povidone-iodine were changed.

[0068] The concentration of povidone iodine in treatment group 4-1 was 0.3 ml / m 3 ; The concentration of povidone iodine in treatment group 4-2 was: 0.4 ml / m 3 ; The concentration of povidone iodine in treatment group 4-3 was: 0.5ml / m 3 ; The concentration of povidone iodine in treatment group 4-4 was: 0.6 ml / m 3 ; The concentration of povidone iodine in treatment groups 4-5 was: 0.75 ml / m 3 ; The concentration of povidone iodine in treatment groups 4-6 was: 0.8 ml / m 3 ; The concentration of povidone iodine in treatment groups 4-7 was: 0.9 ml / m 3 .

[0069] Treatment Group 5: This treatment group included multiple groups (30 longnose catfish fry in each group) to explore the concentration conditions of formaldehyde. The experimental process was basically the same as that of Treatment Group 1, except that the concentration conditions of formaldehyde changed.

[0070] Among them, the formaldehyde concentration of treatment group 5-1 was 50 ppm; the formaldehyde concentration of treatment group 5-2 was 70 ppm; the formaldehyde concentration of treatment group 5-3 was 90 ppm; the formaldehyde concentration of treatment group 5-4 was 100 ppm; the formaldehyde concentration of treatment group 5-5 was 120 ppm; the formaldehyde concentration of treatment group 5-6 was 130 ppm; and the formaldehyde concentration of treatment group 5-7 was 150 ppm.

[0071] Treatment Group 6: This treatment group explored the processing time of the first system formed by sodium chloride and formaldehyde. The operation method was basically the same as that of Treatment Group 1, except that a different processing time of the first system was set.

[0072] Among them, the incubation time of the first system of treatment group 6-1 was 20 minutes, and the number of cycles of the first and second systems was adjusted to 10 times (10 days) to ensure the consistency of the total administration time; the incubation time of the first system of treatment group 6-2 was 50 minutes, and the number of cycles of the first and second systems was adjusted to 4 times (4 days). The treatment time of the second system was coordinated with the treatment time of the first system, and the total treatment time of the two systems was controlled at about 24 hours.

[0073] The experimental results of treatment groups 1 to 6 are shown in Table 1. Treatment group 1 was placed using the treatment of this scheme, and after the treatment cycle, the survival rate of the fry could reach 93.3%. Treatment group 2 did not adjust the temperature to a higher temperature during the third system culture stage, resulting in a decrease in the survival rate of the fry. The addition of the third system culture stage is necessary. The inventor has tried to completely omit the third system culture stage based on treatment group 1 (after the first and second stages of treatment are completed, the fry are cultured under normal conditions without controlling salinity and temperature), which will result in a much lower survival rate of the fry than treatment group 2.

[0074] The use of povidone iodine is necessary for this treatment plan. If the treatment group 1 is referred to but povidone iodine is not added in the second system at all, the survival rate of young fish will be far less than 80%. The specific situation or timing of the use of povidone iodine will affect the effect of the treatment system of this scheme. Treatment group 3 placed the povidone iodine used for the second system in the first system, resulting in a very serious decrease in the survival rate of young fish, and no effective treatment was obtained. This shows that povidone iodine is divided into two spatially and temporally isolated systems with sodium chloride and formaldehyde, and the application of drugs is very critical for improving the effect of drug treatment. Prior art reports have shown that povidone iodine is also a chemical that has an inhibitory effect on Ichthyophthirius spp. The inventor first thought of using povidone iodine in combination with sodium chloride and formaldehyde. However, in fact, if the three substances are applied at the same time and space, the treatment effect of Ichthyophthirius spp. on young fish is not ideal. Povidone iodine needs to be applied to young fish after sodium chloride and formaldehyde treatment to fully improve the effect of the treatment plan.

[0075] In addition, the inventor also explored other ways of using the three drugs, and finally determined the best technical solution of this patent. For example, the parameter conditions of the first system are: sodium chloride with a final concentration of 5‰, formaldehyde with a final concentration of 100ppm, and a final concentration of 0.5ml / m 3povidone iodine (povidone iodine is added every other day, and the frequency of addition is the same as that of the second system), water temperature is 28℃, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L. The second system is the same as treatment group 1, and the treatment process is the same as treatment group 1. In this way, povidone iodine is added to both the first and second systems. Theoretically, in the first system, povidone iodine acts in combination with sodium chloride and formaldehyde. The increase in medication has a stronger inhibitory effect on Ichthyophthirius spp. and promotes its shedding from the fry; in the second system, povidone iodine plays a role in wound disinfection; the working concentration of povidone iodine is not high. Although the contact time of povidone iodine and fry in the first system is increased, this period of time is short, and povidone iodine does not have a toxic effect on fry. According to this operation method, the survival rate of fry and the overall treatment effect should be improved in theory. However, in fact, the survival rate of fry brought about by this operation method is only 83.3%. The inventors further analyzed the reasons for the above phenomenon, which may be that the presence of povidone-iodine affects the synergistic effect of sodium chloride and formaldehyde, and the inhibitory effect on Ichthyophthirius spp. is weakened. This further illustrates that separating povidone-iodine and formaldehyde into two spatially and temporally isolated systems is very critical for improving the therapeutic effect of Ichthyophthirius spp. in long-snouted catfish.

[0076] For treatment groups 4-1 to 4-7, the concentration of povidone iodine was explored, with povidone iodine at 0.3-0.9 ml / m 3 Both can effectively treat Ichthyophthirius, preferably 0.5-0.75 ml / m 3 .

[0077] Treatment groups 5-1 to 5-7 were explored for formaldehyde concentrations. Formaldehyde was tested at 50-150 ppm, and it was found that 90-120 ppm had a better effect, among which 100-120 ppm was more preferred.

[0078] Treatment Group 6-1 and Treatment Group 6-2 explored the combined use of sodium chloride and formaldehyde. Although the same administration time was used as in Treatment Group 1, the time allocation was different, resulting in a significant decrease in the therapeutic effect. Therefore, the combined use of sodium chloride and formaldehyde in the first system administration of this scheme was far superior to others in terms of therapeutic effect, and achieved unexpected technical effects.

[0079] Table 1: Experimental results of treatment groups 1 to 6

[0080]

[0081] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A product for preventing and treating Ichthyophthirius spp., characterized in that: It comprises a first system and a second system for culturing long-snout catfish sequentially and cyclically; The first system comprises a water body containing 3-5‰ sodium chloride and 90-120ppm formaldehyde, a temperature of 26-28°C, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L; the first system is used to culture long-snout catfish for 30-40min; The second system includes water containing 3-5‰ sodium chloride, a temperature of 26-28°C, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L, and the second system is added once every 1-2 days with a final concentration of 0.5-0.75ml / m 3 of povidone-iodine; The second system is used to culture the long-snout catfish treated by the first system; the first system and the second system are used once a day and for 3-14 days; It also includes a third system; the third system includes water containing 3-5‰ sodium chloride, a temperature of 26-28°C, 5mg / L<water dissolved oxygen<9 mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L; the third system is used to culture longnose catfish for one week after the longnose catfish is cyclically treated in the first system and the second system.

2. A product for preventing and treating Ichthyophthirius spp. according to claim 1, characterized in that: The water used for water replacement or water replenishment of the first system, the second system and the third system is stored in a reservoir; the reservoir is first soaked with oxalic acid solution and then cleaned; after water storage, chlorine dioxide is used for disinfection, and then aeration is used to remove residual chlorine.

3. The product for preventing and treating Ichthyophthirius spp. according to claim 2, characterized in that: The first system is a water body containing 5‰ sodium chloride and 100ppm formaldehyde, a temperature of 28°C, 5mg / L<water body dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L; The second system is a water body containing 5‰ sodium chloride, a temperature of 28°C, 5mg / L<dissolved oxygen in the water<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L; The first system is used to treat sick long-snout catfish for 40 minutes every day from the first to the fifth day, and the second system is used to treat sick long-snout catfish after the first system treatment is completed; the second system is added with 0.5-0.75 ml / m 3 of povidone-iodine.

4. The product for preventing and treating Ichthyophthirius spp. according to claim 3, characterized in that: The third system is a water body containing 3‰ sodium chloride, a temperature of 28°C, 5mg / L<water dissolved oxygen<9mg / L, 0mg / L<ammonia nitrogen<0.2mg / L and 0mg / L<nitrite<0.1mg / L.

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