What is the probability that black carp, grass carp, silver carp and carp will suffer from various bacterial fish diseases and their medications?

Polyculture...1. Carp-based farming mode

There is no limit to the size of the fish pond, but The bait coefficient will be higher in large ponds, with water depths of 1.2-1.5 meters. Carp species of different sizes can also be put in in batches to facilitate catching and releasing in turns.

This model mainly feeds compound feed, with more than 30% crude protein, 4-6 times/day, and a feeding rate of 3-8%. Its management points include the traditional "water, seed, etc." In addition to the eight-character essence of ", bait, density, mixing, wheeling, prevention, and management", there is also a new "cross" policy: excellent seeds, refined materials, good water, and meticulous management. Although the first six characters of the new "cross" policy are similar to the experience of the old "eight characters", the new era should include new content, either strengthening or supplementing. The emphasis here is on fine management, which requires the breeding and management personnel not to neglect any link. Even if it is a penny of investment, the output must be calculated. Only in this way can high efficiency be guaranteed.

2. Stocking model with carp as breeding stock

1. Model based on grass carp or bream: 60% grass carp or bream, 15% carp, white silver carp , crucian carp ***25%, suitable for areas with good water sources and more forage.

2. The pattern dominated by white silver carp, 50% silver carp, 15% carp, 30% grass, bream, and crucian carp, is suitable for fatter water bodies.

3. The pattern dominated by spotted catfish is 60% of catfish, 10% of carp, and 30% of silver carp and bream.

4. Crucian carp-dominated model: 60% crucian carp, 10% carp, 10% grass carp, 20% silver carp. The local names of grass carp are Hunzi, grass carp, grass carp, etc.

Cow carp has an elongated body, a slightly sub-cylindrical trunk, flat tail sides, no ventral ribs, a medium-large head, a broad and flat snout, an arc-shaped mouth end, and a slightly protruding upper jaw. Gill rakers are short, rod-shaped, and sparsely arranged. The hypopharyngeal teeth are comb-shaped comb-like teeth, and the scales are quite large and round. The lateral line is slightly curved and extends backward to the middle of the caudal peduncle. The dorsal fin has no hard spines, and its starting point is opposite to the starting point of the pelvic fin, slightly farther from the snout than from the base of the caudal fin. The anal fin has no hard spines, and its starting point is closer to the base of the abdomen than to the base of the caudal fin. The body of the fish is ocher-yellow, with a blue-grey back, gray-white belly, gray-yellow pectoral fins and tail fins, and lighter fins. Grass carp looks very similar to herring, but its body color is different. The body color of grass carp is dark yellow with gray, and the fins are grey-yellow, while the body color of herring is bluish black, and the fins look even more blue-black against the white belly.

Grass carp is widely distributed. Except for Xinjiang and the Qinghai-Tibet Plateau, which have no natural distribution, grass carp is distributed in all major rivers and water systems in my country.

Grass carp generally inhabits the middle and lower layers, and sometimes goes to the upper layers to look for food. Lively and fast swimmer. It is herbivorous. During the fish stage, it mainly feeds on plankton. Young fish also eat aquatic insects. Juvenile fish with a body length of more than 50 mm. Gradually transforms into a herbivore; with a body length of approximately 100 mm, it is fully adapted to feeding on higher aquatic plants. Adult fish mainly feed on higher aquatic plants, such as Vallisneria verticillata, Hydrilla verticillata, Trichophyton algae, Echinacea, duckweed, and turnip. The submerged grassy areas are often the breeding grounds for grass carp. , some dry grasses are also liked by grass carp.

The reproductive mass of grass carp is mainly 4 to 5 years old, mainly individuals with a body length of 650 to 850 mm and a weight of 4 to 9 kg. The smallest female is 4 years old, with a body length of about 540 mm, and a weight of about 2.5 kg; the male is 3 years old, with a body length of about 550 mm, and a body weight of about 2.4 kg. The reproductive season is from early May to early June, and the peak period is mid-to-late May.

Artificial breeding

New fish for grass carp breeding should be fish that are 4 to 5 years old and weigh more than 5 kilograms, with strong physique, good body shape, fast growth, and no trauma or disease. , put it into a broodstock pond of 2 to 4 acres and a water depth of 1.5 to 2.5 meters for cultivation. It is appropriate to stock 100 to 125 kilograms of broodstock per acre, usually 15 to 27 broodstock of 6 to 8 kilograms, and the female to male ratio is 1:1.5. You can raise 5 to 10 silver carp broodstock and 1 to 2 bighead carp broodstock. If there are many snails in the pond, you can also raise 2 to 3 herring. The breeding of broodstock should be strengthened, especially spring breeding (from March to spawning) is more important. Mainly green material should be fed. Appropriate feeding of concentrates can include lettuce leaves, cabbage leaves, etc., as well as grain sprouts or malt. Add new water every 5 to 7 days, adding 3 to 6 cm of water each time. 1 to 2 weeks before delivery, water should be injected every other day to strengthen the flow of water and stimulate the development and maturation of the gonads. For mature broodstock, gently press the abdomen, and eggs or semen can be squeezed out of the reproductive pores. Mature broodstock can be injected with oxytocins such as pituitary gland, chorionic gonadotropin, luteinizing hormone-releasing hormone and similar substances to promote estrus and spawning. They can naturally spawn in estrus in the spawning pool, or artificial insemination can be used. The collected fertilized eggs can be placed in an incubation container and hatched under running water. The hatching density increases or decreases with different containers. Usually, 1 million eggs are placed per cubic meter. It takes about 20 to 32 hours (the peeling time will vary depending on the water temperature) to take off the film. Generally, 3 to 5 days after the film is taken off, the yolk sac of the fry disappears, the swim bladder is inflated and the fish can leave the hatching container and go to the pond.

Fry fry cultivation

Fry fry cultivation refers to the cultivation of fry into summer flower fingerlings of about 3 cm in about 20 days, commonly known as "fat pond". The area of ​​the fry breeding pond is 1 to 2 acres, the depth of the pond is 1.5 to 2 meters, and the water depth is 1 to 1.5 meters. The best shape of the pond is rectangular, with easy access and drainage, and the bottom of the pond is preferably loam. Fish fry ponds should be cleaned and disinfected. The methods include the following:

1. Quicklime: For each mu of fish pond with a water depth of about 1 meter, about 130 to 160 kilograms of quicklime is needed to clear the pond. When dry pond water is disinfected by dry pond cleaning, only 50 to 80 kilograms per mu are needed. When the quicklime water melts and has not cooled down, it can be poured into the entire pool immediately.

After 7 to 10 days of clearing the pond, fry can be added. In addition to clearing and disinfecting ponds, quicklime can also play a role in regulating water quality and fertilizing, with more disadvantages and fewer disadvantages. Therefore, quicklime is commonly used to clear ponds.

2. Bleaching powder: For a fish pond with a water depth of 1 meter per acre, approximately 14 kilograms of bleaching powder will be used. If the water depth is 5 to 10 centimeters, 3 to 5 kilograms are needed. Dissolve bleaching powder in water and pour it over the entire pool. In case of scorching sun, the effect will be better. Fish fry can be released 5 to 7 days after clearing the pond.

3. Ammonia: When the water depth of the fish pond is 10 cm, use more than 50 kg per acre. The dosage is often related to the storage time of ammonia. During operation, the entire pool should be sprayed in a leeward location. If sprayed under the hot sun, the efficacy will be greater.

Generally, water can be injected one day after applying ammonia, and fry can be released after 3 to 5 days. The characteristic of this method is that it can disinfect the pond quickly and the poison will disappear quickly.

4. Rotenone: When the water depth is 1 meter, about 1.3 kilograms of rotenone should be used per acre of fish pond. Commercially available rotenix actually contains 2.5%, 5%, and 7.5% emulsifiable concentrate. During operation, add water 10 to 15 times (effective depth is about 2PPm) to dilute it and then pour it into the entire pool. Seedlings can be released 7 days after clearing the pond.

5. Tea meal: When the water depth per mu is 1 meter, use 35 to 40 kilograms of tea meal. During operation, first mash the tea cake into small pieces, put it in a water tank and soak it in water for a day, take it out, then add a large amount of water to dilute it, stir it evenly, and then pour the residue into the whole tank. The toxicity disappears in about 7 to 10 days.

6. Sodium pentachlorophenate, dimethyl tetrachloride, and prometryn mixture: When the pool water is about 13 to 30 centimeters, use 1 kilogram of sodium pentachlorophenate (65% water-soluble original powder) per acre. , 75 grams of dimethyl tetrachloride (70% water-soluble powder), and 150 grams of promethazolin (50% wettable powder). Mix them and add water to dissolve them, and sprinkle them evenly throughout the pool.

Generally, water is added 10 to 15 days after pesticide application, and then base fertilizer is applied. After about 2 to 3 days, the water can be tested. If it is non-toxic, fry can be released into the pond.

7. Sodium pentachlorophenate: 2 kilograms per mu of pond (water depth 0.5 meters), soak the entire pond for 5 to 7 days, drain the water, and expose for 4 to 5 days, that is Can be filled with water.

The fry pond can be filled with new water after the clear pond is disinfected. When filling the water, filter it with a sieve at the water inlet and fill 40 to 50 centimeters of water. Base fertilizer should be applied before the fry are put into the pond. Generally, medium fertilizer is suitable for the fry. That is, 3 to 5 days before the fry are released, 200 to 400 kilograms of livestock manure, or 50 to 100 kilograms of manure, are generally applied per mu. If you need to speed up fertilization, you can use inorganic fertilizers. Generally, 5 to 10 kilograms of ammonia per mu, and 2.5 to 5 kilograms of ammonium sulfate and ammonium nitrate per mu. By applying base fertilizer, the zooplankton and plants in the water will grow rapidly, and the water color will turn to light green or light brown, and the fish fry can be stocked for cultivation.

When raising fry, you should choose a group of fish that are uniform in size, fresh in color, plump and well-proportioned, and swimming and active. Generally, 100,000 to 120,000 grass carp fry are stocked per acre; if the fish pond area is large, 200,000 grass carp fry can be stocked per acre.

The methods of raising fry vary from place to place, including soy milk raising, grass raising, pig manure raising, etc. Most of the people in this area adopt soybean feeding methods. After the fry enter the pond, the first soy milk should be fed every 5 to 6 hours. For example, if the fry enter the pond in the afternoon, they should be fed in the afternoon. Usually twice a day, 8-9 am and 14-15 pm. No later than 16:00. Within 10 days after the fry are placed in the pond, feed 1.5 to 2 kilograms of soybeans or 2 to 2.5 kilograms of soaked soybean cakes per mu per day. After 10 days, increase or decrease as appropriate according to the fatness of the water quality. If it rains and the temperature is low, soy milk must be added. According to the dosage, the soy milk should be poured evenly throughout the pool. If combined with fertilization, the amount of bean cake or soybeans can be reduced. Generally, fertilization can be done 4 to 5 days after the fry are released into the pond.

New water should be added regularly during the fry cultivation period. When the fry enter the pond, the water in the pond is generally about 50 cm. 4 to 5 days after the fry enter the pond, 10 cm of water should be added, and thereafter every 3 to 4 days. Add new water once so that the fry will grow to the summer flowering stage and the pool should be about 1 meter long. When adding new water, strict precautions should be taken to prevent wild fish and other fish from mixing into the pool. Strengthen pond patrols to help identify problems and resolve them in a timely manner. If there is water leakage in the fish pond, it should be blocked in time. Remove fertilizer residue, soy milk foam, etc. from the water surface in a timely manner to keep the pond water environment clean and prevent and control fish diseases. After being cultivated for 20 to 30 days after the fry are put into the pond, summer flowering fish species that can generally grow to about 3 cm should be cultured in separate ponds. Before the summer flower fish species emerge from the pond, they should undergo a second net-drawing exercise before leaving the pond.

Generally, about 20 days after the fry are released into the pond, they are caught in the pond with a dense fish net. The time should be chosen between 8 and 9 a.m. on a sunny day. The fish are enclosed in the net and the wild fish are picked out. After a few minutes, they are returned to the original pond. , use the same method after one day, gather the fish into the net, lift the net, dump all the fish into the cage, slowly drag the cage, let the fish swim against the water for 1 to 2 hours, and put the fish into the pond middle. After the second net-drawing exercise, the summer flowers are strong and can be taken out of the pond to be nourished.

Fingerlings Breeding

Grass carp fingerlings are generally raised from summer flower fingerlings to first-age fingerlings of about 13.2 cm in the first year, also known as Zaikou grass carp fingerlings; Then the second-age fish fingerlings with a size of 23.1 to 26.4 centimeters or 0.25 to 0.5 kilograms, also known as Laokou grass carp fingerlings, can be raised to 2 to 3 kilograms of adult fish after another year of breeding.

There has been a lot of experience in high-yield grass carp fingerlings in recent years. Here are a few examples:

Example 1: High-yield breeding of grass carp fingerlings.

The pond area is about 4 acres, the average water depth is about 2.5 meters, and drainage and irrigation are convenient. According to party regulations, use 75 kilograms of quicklime per acre to completely clear the pond. Apply 1 ton of fermented cow dung per acre about 10 days before the summer croaker is planted in the pond. When the summer flowers are put into the pond, the water color will be yellowish brown, the transparency will be 25 centimeters, and the water depth will be 1.5 meters.

When summer fish species are stocked, the main body of grass carp should be released first, multiple species should be mixed and stocked closely, and the time for stocking silver carp should be controlled. On June 4, 9,300 summer grass carp with a height of 3.6 to 4.3 cm were released per mu, weighing 6 kg; on June 26, 1,744 crucian carp with a weight of 0.45 kg were released; on June 30, 1,172 bighead carp with a diameter of 4.9 cm were released. The weight is 1.4 kg; on July 1, 2,585 2.9 cm silver carp were released, weighing 0.60 kg, and the total amount released per mu was 14,751 fish, with a total weight of 8.45 kg.

At the end of the year, 1,504 and 1,193 grass carps of 75 g/tail and 165 g/tail were caught per mu, respectively, weighing 310 kg; 1,167 crucian carp of 60 g/tail, weighing 70 kg; 70 There are 1,110 bighead carps per gram, weighing 78 kilograms; 2,074 silver carp fingerlings per 100 grams, weighing 207 kilograms; the average number of fish fingerlings per mu is 7,048, with a yield of 665 kilograms.

After summer grass carp enters the pond, feed turnip and duckweed. When the summer grass carp grows to 7 centimeters, feed chopped tender grass instead. After 10 centimeters, feed green grass directly. The amount of feeding depends on the growth, feeding and weather conditions of the fish. Feed less on rainy, muggy days and less on sunny days. Feed more. The feed is generally controlled to be consumed within 3 hours after the concentrate is fed, and the green feed is preferably consumed within 4 to 5 hours. Each acre uses 3260 kilograms of fodder and 1260 kilograms of concentrate.

Strengthen water quality management. Add new water once every 2 to 3 days in the early breeding period, with an amount of 20-30 cm; from mid-July to early October, add water once a day with an amount of 25-30 cm. As the number of water injections increases, the water depth remains above 2.5 meters. After mid-October, add water depending on the water quality. The time to add water is generally 6 o'clock in the morning, and the middle stage of cultivation is around 1 o'clock in the night.

The main thing is to prevent fish diseases. In addition to thoroughly cleaning the pond, pay attention to adjusting the water quality after the summer flowers enter the pond. During the fish disease epidemic season, alternately splash bleaching powder and quicklime every 7 to 10 days. For different fish diseases, copper sulfate and ferrous sulfate mixtures, rhubarb, trichlorfon, garlic and other ingredients are used for feeding.

Example 2: The breeding pond mainly uses grass and bream species, with an area of ​​6.1 acres, a water depth of 2.5 meters, and irrigation and drainage by water pumps. The number of fish species stocked per acre is 5,000 grass carp with summer flowers on July 2; 6,000 summer bream with summer flowers on June 11; 3,000 crucian carp with summer flowers on June 27; and silver carp and bighead carp with summer flowers on July 15. 3000 tail. By the end of the year, the average yield per mu was 611.15 kilograms. Among them, there are 1,085 100 g/tail grass carp species, weighing 108.6 kg; 5,372 31.25 g/tail bream species, weighing 167.85 kg; 1,946 41.7 g/tail crucian carp species, weighing 81.065 kg; 122 g/tail 2,029 silver carp and bighead carp species. Tail/253.5kg.

Rearing method: Use poultry and livestock manure to cultivate the water quality 10 days before the summer fish is planted in the pond, and the water level in the pond is about 1 meter. Summer flower fingerlings should be stocked with uniform sizes. When entering the pond, soak the fish fingerlings in 3 to 4% salt water for 5 to 10 minutes. When stocking, the main grass and bream should be released first, and crucian carp, silver carp and bighead carp should be released at the right time. After stocking, water is gradually added to deepen the water level. In late July, the water quality is prone to deterioration. The bottom water is frequently pumped out and new water is injected, and the aerator is fully used to increase oxygen. Use 20-30PPm lime water to adjust the water quality every 15-20 days in July, August and September, and use it alternately with phosphate fertilizer to keep the water quality stable and weakly alkaline. The feed should be a combination of refined and green feed. The concentrated feed is fed in a quantitative manner, and 1% salt is added; the green feed is fed with appropriate and palatable green feed to meet the needs as much as possible. Feed well, feed well and evenly in the 7th, 8th and 9th months, accounting for about 60-70% of the feeding amount. Concentrate feeding should be increased or decreased according to weather and feeding conditions.

Do a good job in preventing and controlling fish diseases. In addition to routine disease prevention before the beginning of autumn, mix 6 grams of furazolidone per 100 kilograms into the daily feeding amount and process it into pellet feed for feeding. A course of treatment is three days, once a month; or mix it with 1% bleaching powder leaching solution Feed into the feed.

Adult fish breeding

The size of the adult fish breeding pond is 4 to 10 acres, and the water depth is about 2.5 meters. It must have good inlet and drainage conditions, and it is best to be able to drain quickly. Fast irrigation; equipped with an aerator at 0.25 to 0.50 kilowatts per mu.

The fish stocking should be based on herbivorous fish (grass carp or bream), which can make full use of green feed resources. When matching fish, crucian carp should be highlighted and other fish should be taken into account. The use of interculture methods can improve pond utilization and improve economic benefits.

Water quality management aims at thick water in spring and autumn and light water in summer and autumn. The control of main water quality indicators focuses on the three main lines of dissolved oxygen, non-ionic nitrogen, and carbon dioxide balance systems. Apply organic fertilizers and supplementary phosphate fertilizers in winter; do not apply organic fertilizers in high-temperature seasons, and rationally use aerators, water supplements, quicklime, bleaching powder and other technical measures to improve water quality.

It is better to use grass and bream compound feed. If a single feed is used, plant feed with higher protein content should be used, and at the same time, concentrate and green feed should be combined. Feeding should be based on the fish growth rate, survival rate index, overall weight gain, and feed coefficient to calculate the total feeding amount, and then feed it daily according to the distribution amount for 5 days. And increase or decrease as appropriate according to weather, food intake and other conditions.

Focus on fish disease prevention and combine prevention and treatment.

In recent years, with the development of high-yield breeding technology of pellet feed, there are many better stocking models for mixed breeding. Here are a few examples for reference.

Example 1:

The breeding performance of grass carp and bream as the main fish, with a net output of 500 kilograms per mu.

The pond is 5.2 acres.

The average fish stocking per mu is 568 grams/55 grass carp; 29 grams/tail 160 grass carp; 150 grams/tail 100 bream; 14 grams/tail 600 bream. 50 carp/tail of 50g, 300 summer flower carp, 200 crucian carp/tail of 52g, 40 silver carp/tail of 346g, 260 silver carp/tail of 77g, 16 bighead carp/tail of 392g, 50g/50 bighead carps. A total of 1,831 animals were released per mu, weighing 115.9 kilograms.

The average net yield per mu is 3019 grams/tail, grass carp 122.4kg, 990g/tail grass carp 129.9kg, 313g/tail bream 11.9kg, 200g/tail bream 51.4 Kilogram, 747g/tail carp 32kg, 202g/tail carp 19kg, 178g/tail crucian carp 18.3kg, 1000g/tail silver carp 24.2kg, 622g/tail silver carp 134.1kg, 1051g/tail bighead carp 9.7kg, 655g/tail bighead carp 29.6kg. The total net yield per mu is 582.5 kilograms.

In the above example, in the feeding management, in addition to feeding concentrated feed and green feed, it is also necessary to apply fertilizer and water, control the water color, and be equipped with an aerator.

Example 2:

The area is 9.1 acres

The average fish stocking per mu is 417 grams/126 grass carp, 10 grams/358 grass carp, 88 71g/tail bream, 210 13g/tail bream, 40 125g/tail carp, 145 24g/tail carp, 430 34g/tail crucian carp, 59g/tail silver carp 335 fish, 69g/tail, 72 bighead carps. A total of 113 kilograms of fish fingerlings are stocked per mu.

The average net yield per mu is 1750g/tail grass carp 156.9kg, 266g/tail grass carp 67.8kg, 250g/tail bream 14.6kg, 67g/tail bream 8.6kg , 1216g/tail carp 40.8kg, 550g/tail carp 72.2kg, 241g/tail crucian carp 83.6kg, 738g/tail silver carp 227kg, 43.5g/tail bighead carp 111.6kg. The total net yield per mu was 783.1 kilograms.

Due to the high fish capacity, the above examples must be equipped with aerators and good inlet and drainage facilities. In terms of feeding and management, concentrate feed and green feed are mainly fed, and the amount of fertilizer is small.

Fish disease prevention and control

1. Hemorrhagic disease:

It is a viral fish disease. The surface of the fish is generally dark and slightly red, with bleeding under the skin and muscles, congestion in the mouth, lower jaw, top of the head or around the eye sockets, and even protruding eyeballs, congestion at the base of the gill cover and fin rays.

Prevention and treatment methods: Injecting fish species with inactivated vaccine can prevent it. For every 50 kilograms of fish, beat 4 to 5 kilograms of peanuts, 0.25 kilograms of garlic and salt together into a paste, mix with 1.5 kilograms of water bran to make a medicinal bait and feed it once a day for 5 consecutive days; at the same time, the water depth per mu is 0.33 meters. Add 110 grams of copper sulfate to the appropriate amount of water and then pour it over the entire pool for 5 consecutive days. For every 10,000 fish fingerlings, grind 0.25 to 0.5 kg of rhubarb or liquidambar leaves into powder, decoct or soak in hot water overnight, mix with feed and feed for 5 consecutive days. Apply copper sulfate, copper acetate, or copper chloride to a depth of 0.7PPm for two days.

2. Erythroderma: also known as hemorrhagic putrefaction.

Symptoms include local or large hemorrhage on the fish body surface, loss of scales, most obvious on both sides of the fish body and abdomen, congestion at the base of some or all fin rays, slight rot at the end of the fins, gill cover and fish Red patches often appear on the upper and lower jaws. Sick fish often swim alone in the water and move slowly.

Prevention and control methods: Fish diseases and injuries should be prevented during fishing, transportation, stocking and other operations. Soak with 5-10PPm bleaching powder solution for half an hour before stocking. Add sulfathiazole to the feed, and the dosage is calculated as 1 gram for 10 kilograms of fish, and feed it continuously for 6 days. For external disinfection, bleach can be poured into the entire pool.

3. Leukoderma: also known as white tail disease.

The symptoms begin with the appearance of small white spots on the base of the dorsal fin or caudal peduncle of the diseased fish, which quickly expand, making the skin behind the dorsal fin white, the scales falling off, and the tail fin can ulcerating and saprolegnia occurs immediately, which can easily cause die. Often appears in summer flowers and fingerling stages.

Prevention and treatment methods: Fish should be prevented from being injured during operation. Before stocking fish, soak them with 2-3PPm mercury nitrate for 2 hours; sick fish can also be soaked, which has a therapeutic effect. When the disease is serious, 1PPm bleaching powder can be poured into the whole pool, 1g per cubic meter.

4. Saprolegnia:

The fungus invades from the skin of fish body wounds, parasitizes on the epidermal tissue, and reproduces and spreads. The surface of the body appears as cotton-like colonies, which are gray-white or light blue. . Can easily cause death.

Prevention and control methods: The fish pond should be thoroughly cleaned with quicklime before stocking to reduce pathogens. Care should be taken during operation to reduce fish damage. Sick fish can be soaked in 0.015PPm malachite green solution for 2 to 10 minutes.

5. White spot disease, also known as small melon seed disease.

It is caused by a large number of parasitic parasites of small melon worms, and small white dot-like vesicles appear on the surface of the fish body such as the gill cover. In severe cases, the surface of the fish will be covered with a white film, the mucus on the body surface will increase, the fish will become thin, swim slowly, and float on the water.

Prevention and control methods: Fish ponds should be thoroughly disinfected with quicklime to reduce pathogens. Sick fish can be soaked in a mixed solution of 1/50,000 copper sulfate and magnesium sulfate plus 1% salt for 20 to 30 minutes to kill all small melon seed insects.

6. Anchocephalosis, also known as anchocephalosis and needleworm disease.

Anchor-headed turtles can be seen on the surface of the diseased fish. The tissues around the insect body are red, swollen, inflamed, and even ulcerated. The scales near the wound are dissolved and rotted into gaps by insect body secretions.

Prevention and control methods: Thoroughly clear the fish pond with quicklime to kill the larvae and eggs of the worm. Strictly prohibit sick fish from entering the pond to cause infection. Soak the sick fish in a solution of potassium permanganate that is 1/50,000 (when the water temperature is 15 to 20°C) or 1/100,000 (when the water temperature is 21 to 30°C) for 1.5 to 2 hours.

7. Bacterial gill rot

The symptoms are that the inner wall of the gill bones is congested and sometimes ulcerated; the gill filaments are rotten and white in color, and the cartilage at the tip of the gill filaments is exposed. In severe cases, the gill flaps The edges become rotten and spread to the entire gill valve. Fish with the disease often swim alone, move slowly, and have dark body color.

Prevention and control methods: When stocking fish species, soak them in a solution of 1/100,000 bleaching powder for 30 minutes. Sprinkle bleach all over the pool.

8. Intestinal inflammation

The symptoms are redness and swelling of the anus. In severe cases, blood or yellow mucus may flow out of the anus by gently pressing the abdomen. Part or all of the intestinal tract is inflamed and turns purple.

Prevention and treatment methods: Add 10 to 15 grams of furazolidine to every 50 kilograms of feed, make it into a medicinal bait and feed it once a day for 5 to 6 days in a row

1. Bacteria Sexually transmitted fish diseases: mainly include printing disease of silver carp and bighead carp and red skin disease of grass herring. These two diseases are caused by mechanical damage and bacterial invasion. The prevention and control method is: before placing the fish in the pond, soak it in 5% salt water for 3-5 minutes. After placing the fish in the pond, regularly use 1ppm bleach (or 0.5ppm chlorine, 0... It is best to cultivate large sizes in your own pond. For crucian carp fingerlings, 8,000 to 12,000 crucian carp fry are stocked per acre, and they are cultivated to 50-60 grams before being transferred to ponds for adult fish breeding. The breeding density is 1,500-1,800 crucian carp fingerlings of 50-60 grams per acre. This is good, so that the size of commercial fish can reach more than 350-400 grams.

To cultivate large-sized crucian carp species with varieties, silver carp and bighead carp should be selected for mixed culture. The number of silver carp accounts for 20% of the main crucian carp. Bighead carp accounts for about 10% of silver carp. The stocking time of matching species silver carp and bighead carp should not be too early, because too early will affect the domestication of crucian carp.

The domestication of crucian carp is the key to survival. Fish in the middle and lower layers of the water body, and fish ponds that mainly raise crucian carp, must acclimatize the fish species, which is very conducive to the growth of crucian carp.

Five points should be noted during domestication: First, domestication is relatively easy during the fish breeding stage; second, appropriate amounts of additives can be added to the feed during domestication to shorten the domestication time; third, when the stocking density has been determined, the pond can be lowered during the domestication. The water level will relatively increase the density, which is more conducive to domestication; fourth, silver carp and bighead carp species should be released after the main crucian carp has formed a habit of floating up to grab food; fifth, during the domestication period, the pond water quality should be "lean" and not "turbid and fat".

Feed particle size The feed particle size for feeding crucian carp should be “small but not large”. Crucian carp with a size of less than 10 grams should choose feed with a particle size of 0.5 mm, 1 mm for 10-30 g, 1.5 mm for 30-75 g, 2 mm for 75-100 g, and 2 mm for 150-300 g. Choose 2.5mm if it weighs 300g or more, choose 3.2mm if it weighs more than 300g.

The feeding rate of crucian carp breeding ponds should depend on the size of crucian carp and the pond water temperature. When the water temperature is lower than 15℃, the feeding rate should be the lowest value; when the water temperature is 16-23℃, the feeding capacity of crucian carp is relatively high. Strong, the feeding rate should be averaged; when the water temperature is 24-29°C, crucian carp has the strongest appetite, and the feeding rate should be the highest value to ensure sufficient food.

Disease prevention and treatment Hemorrhagic anchorhead disease is more harmful to crucian carp. Its main characteristics are that the crucian carp is unable to swim slowly in the water and is pale in color. Needle-like parasites can be seen on the surface, abdomen and both sides of the back of the fish. There is a congested erythema the size of a mung bean or pea at the insertion site. During the disease season, sprinkle 0.3 grams of 90% crystalline trichlorfon per cubic meter every half month in the main breeding pond with a small area; for large-area crucian carp breeding ponds, hang baskets (bags) of trichlorfon around the food court, and spray them every 1-2 times a month, for 2 days each time, all have good preventive effects. For diseased ponds, 0.5 grams of 90% crystalline trichlorfon and 0.2 grams of ferrous sulfate mixture can be sprayed per cubic meter at one time, which has a better effect.