CATDOLL : CATDOLL: How are carp, grass carp, silver carp, bighead carp, crucian carp and bighead bream raised in the south?

Can be mixed cultured.....1. Carp-based culture model

There is no limit to the size of the fish pond, but the bait coefficient of a large pond will be higher. The water depth is 1.2-1.5 meters. Carp of different sizes can also be released in stages and batches to facilitate rotation of capture and release.

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

2. Stocking model with carp as a companion

1. The model mainly based on grass carp or bighead carp: grass carp or bighead carp 60%, carp 15%, silver carp and crucian carp 25% in total, suitable for areas with good water sources and abundant grass.

2. The model with silver carp as the main species is 50% silver carp, 15% carp, and 30% grass carp, bream, and crucian carp. It is suitable for fertile water bodies.

3. The pattern with spotted and tailed t as the main species is forktail t 60%, carp 10%, silver carp and bream 30%.

4. The model dominated by crucian carp: crucian carp 60%, carp 10%, grass carp 10%, silver carp 20%. The local names of grass carp are hunzi, silver carp, and caoqing, etc.

The grass carp has an elongated body, a slightly sub-cylindrical trunk, a flat tail, no ventral ridges, a medium-sized head, a wide and flat snout, an arc-shaped mouth, and a slightly protruding upper jaw. The gill rakers are short and rod-shaped, sparsely arranged. The hypopharyngeal teeth are comb-shaped, with large, round scales. The lateral line is slightly curved, extending 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 tip of 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 fish body is tea-yellow, with a blue-gray back, a gray-white abdomen, and gray-yellow pectoral and caudal fins, while the other fins are lighter. The grass carp looks very similar to the black carp, but the two have different body colors. The grass carp has a tea-yellow body color with gray, and its even fins are gray-yellow, while the black carp has a blue-black body color, and its even fins appear even more blue-black against the white abdomen.

Grass carp is widely distributed. Except in Xinjiang and the Qinghai-Tibet Plateau, it is distributed in all major river systems in my country.

Grass carp generally inhabits the middle and lower layers, and sometimes goes to the upper layer to forage. It is lively and swims fast. It is herbivorous. It mainly feeds on plankton during the fish stage, and juveniles also eat aquatic insects. Juveniles with a body length of more than 50 mm gradually turn into herbivores; when the body length reaches about 100 mm, it can fully adapt to eating aquatic higher plants. Adult fish mainly feed on higher aquatic plants, such as Vallisneria, Hydrilla verticillata, Algae, Potamogeton, Duckweed, and Duckweed as the most favorite species; flooded grassy areas are often the fattening places for grass carp, and some dry grasses are also favored by grass carp.

The reproductive population of grass carp is mainly 4 to 5 years old, with a body length of 650 to 850 mm and a weight of 4 to 9 kg. The smallest female is 4 years old, about 540 mm long and weighs about 2.5 kg; the male is 3 years old, about 550 mm long and weighs 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 selected from fish that are over 4 to 5 years old, weigh more than 5 kg, have a strong physique, good body shape, fast growth, no external injuries and symptoms, and be placed in a broodstock pond of 2 to 4 mu and 1.5 to 2.5 meters deep for cultivation. It is appropriate to stock 100 to 125 kg of broodstock per mu, generally 15 to 27 6 to 8 kg grass broodstock, and the ratio of female to male is 1:1.5. 5 to 10 silver carp broodstock and 1 to 2 bighead carp broodstock can be raised together. When there are many snails in the pond, 2 to 3 black carps can also be raised together. Parent fish should be cultivated more intensively, especially in spring cultivation (from March to spawning). Green feed should be fed as the main feed. Appropriate feed should be fed with fine feed, such as lettuce leaves, cabbage leaves, etc., and can be fed with grain sprouts or malt. New water should be added every 5 to 7 days, and 3 to 6 cm of water should be added each time. 1 to 2 weeks before spawning, water should be added every other day to strengthen the flow of water to stimulate the maturation of gonads. For mature broodstock, gently press the abdomen, and eggs or semen can be squeezed out of the reproductive hole. Mature broodstock can be injected with oxytocin such as pituitary, chorionic gonadotropin, luteinizing hormone-releasing hormone and similar agents to promote estrus and spawning. They can estrus and spawn naturally in the spawning pool, or artificial insemination methods can be used. The collected fertilized eggs can be placed in the incubation container for incubation in running water. The incubation density varies with the container. Usually 1 million eggs are placed per cubic meter. The membrane can be removed after about 20 to 32 hours (depending on the water temperature, the membrane removal time varies). Generally, 3 to 5 days after the membrane removal, the yolk sac of the fry disappears, and the swim bladder is inflated and can be taken out of the incubation container and put into the pond.

Fish fry cultivation

Fry cultivation refers to the process of cultivating fry into 3 cm long summer flower fish in about 20 days after the fry are laid, commonly known as "fa pond". The fry cultivation pond area is 1 to 2 mu, the pond depth is 1.5 to 2 meters, and the water depth is 1 to 1.5 meters. The pond shape is preferably rectangular; it is convenient for water inlet and outlet, and loam is the best pond bottom. The fry pond should be cleaned and disinfected, and there are many ways to do it:

1. Quicklime: For each acre of fish pond with a water depth of about 1 meter, 130 to 160 kilograms of quicklime are needed for pond cleaning. If the pond water is drained and the pond is disinfected by dry method, only 50 to 80 kilograms per acre are needed. When the quicklime water melts but has not cooled, it can be immediately poured over the entire pond.

Fish fry can be put in 7-10 days after pond cleaning. In addition to pond cleaning and disinfection, quicklime can also play a role in regulating water quality and fertilization, with more benefits and fewer disadvantages. Therefore, quicklime is widely used for pond cleaning.

2. Bleaching powder: For every acre of fish pond with a water depth of 1 meter, use about 14 kg of bleaching powder. If the water depth is 5-10 cm, use 3-5 kg. Dissolve the bleaching powder in water and sprinkle it all over the pond in the leeward direction. The effect will be better in the hot sun. 5-7 days after cleaning the pond, you can release the fry.

3. Ammonia water: When the water depth of the fish pond is 10 cm, use more than 50 kg per mu. The amount is often related to the length of storage time of ammonia water. When operating, it is necessary to spray the whole pond in the leeward place. If it is sprayed under the scorching sun, the effect will be greater.

Generally, water can be added one day after ammonia water is applied, and fish fry can be released 3 to 5 days later. The characteristics of this method are fast pond cleaning and disinfection, and the poison disappears quickly.

4. Rotenone: When the water depth is 1 meter, use about 1.3 kg of rotenone per mu of fish pond. The commercially available rotenone is actually an emulsion containing 2.5%, 5%, and 7.5%. When operating, add 10 to 15 times of water (effective depth is about 2PPm) and dilute it, then sprinkle it all over the pond. After clearing the pond for 7 days, you can stock the fish.

5. Tea dregs: When the water depth is 1 meter per mu, use 35-40 kg of tea dregs. When operating, first crush the tea dregs into small pieces, put them in a water tank and soak them for one day, then add a large amount of water to dilute them, stir them well, and then sprinkle them all over the pond with the dregs. The toxicity disappears in about 7-10 days.

6. Mixture of sodium pentachlorophenol, dimethoate and promethazine: When the pond water is about 13 to 30 cm, use 1 kg of sodium pentachlorophenol (65% water-soluble original powder), 75 g of dimethoate (70% water-soluble powder), and 150 g of promethazine (50% wettable powder) per mu. Mix them, add water to dissolve, and sprinkle evenly throughout the pond.

Generally, add water 10 to 15 days after applying the pesticide, and then apply base fertilizer. After about 2 to 3 days, you can test the water. If it is non-toxic, you can put fish fry into the pond.

7. Sodium pentachlorophenol: Use 2 kg of the drug per acre of pond (water depth 0.5 meters). Spray it all over the pond and soak it for 5 to 7 days. Drain the water, expose it for 4 to 5 days, and then fill it with water.

After the fish fry pond is cleaned and disinfected, new water can be poured into it. When pouring water, it should be filtered with a silk sieve at the water inlet, and the water should be poured 40 to 50 cm. Basal fertilizer should be applied before the fish fry are put into the pond. Generally, medium fertilizer is better for the fish fry. That is, 3 to 5 days before the fish fry are put into the pond, generally 200 to 400 kg of animal manure or 50 to 100 kg of manure should be applied per mu. If you need to accelerate the fertilization of water, you can use inorganic fertilizers, generally 5 to 10 kg of ammonia water per mu, and 2.5 to 5 kg of ammonium sulfate, ammonium nitrate, etc. per mu. By applying basal fertilizer, the plankton and plants in the water grow rapidly, and the water color turns to tender green or light brown, and the fish fry can be put into the pond for cultivation.

When stocking fish fry, you should choose fish of uniform size, fresh color, plump and evenly symmetrical, and active. Generally, 100,000 to 120,000 grass carp fry are stocked per mu; if the fish pond area is large, 200,000 fry can be stocked per mu.

The methods of raising fry vary from place to place, including soy milk, grass, pig manure, etc. Most of the methods used in this area are soybean raising. After the fry are put into the pond, the first soybean milk should be fed every 5 to 6 hours. If they are put into the pond in the afternoon, they should be fed in the afternoon. Generally, it is fed twice a day, at 8 to 9 am and 14 to 15 pm. No later than 16 pm. Within 10 days after the fry are put into the pond, 1.5 to 2 kg of soybeans or 2 to 2.5 kg of bean cakes are soaked and ground into pulp per mu every day. After 10 days, the amount can be increased or decreased according to the fatness and thinness of the water quality. If it rains and the temperature is low, the amount of soybean milk should be increased as appropriate. The soybean milk should be evenly sprinkled throughout the pond. If combined with fertilization, the amount of bean cake or soybeans can be reduced. Generally, fertilization can be applied 4 to 5 days after the fry are put into the pond.

During the period of fish fry cultivation, new water should be added regularly. When the fish fry are put into the pond, the pond water is generally about 50 cm. 4 to 5 days after the fish fry are put into the pond, 10 cm of water should be added. After that, new water should be added every 3 to 4 days, so that the pond should reach about 1 meter when the fish fry are cultivated to the summer flowering stage. When adding new water, wild fish and other fish should be prevented from mixing into the pond. Strengthen the inspection of the pond to facilitate the discovery of problems and timely solve them. Whether there is water leakage in the fish pond, it should be blocked in time. Remove fertilizer residues and soy milk foam on the water surface in time to keep the pond water environment clean and do a good job in fish disease prevention and control. After 20 to 30 days of cultivation after the fish fry are put into the pond, they can generally grow to about 3 cm of summer flower fingerlings, which should be cultured in separate ponds. Before the summer flower fingerlings are taken out of the pond, they should be trained by pulling the net twice before they can be taken out of the pond. Generally, about 20 days after the fry are put into the pond, they are caught in the pond with a fine-meshed fish net. The time should be selected at 8-9 am on a sunny day. The fish are enclosed in the net and wild fish are picked out. After a few minutes, they are put back into the original pond. After a day, the same method is used to enclose the fish in the net, lift the net, and pour all the fish into the net cage. The net cage is slowly dragged to make the fish swim against the water for 1-2 hours, and then the fish are put into the pond. After the second net-pulling exercise, the summer flowers are strong and can be taken out of the pond for separate breeding.

Fingerling farming

In the first year of grass carp fingerling breeding, generally, grass carp are raised from summer flower fingerlings to one-year-old fingerlings of about 13.2 cm, also known as juvenile grass carp fingerlings; in the second year, they are raised to two-year-old fingerlings of 23.1-26.4 cm or 0.25-0.5 kg, also known as old grass carp fingerlings. After another year of breeding, they can be raised to adult fish of 2-3 kg.

Grass carp has a lot of experience in high yield in recent years. Here are a few examples:

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

The pond area is about 4 mu, with an average water depth of about 2.5 meters, and it is easy to drain and irrigate. According to the party regulations, 75 kg of quicklime is used per mu to thoroughly clean the pond. About 10 days before the summer flower fish is planted in the pond, 1 ton of fermented cow dung is applied per mu. When the summer flower is planted in the pond, the water color is yellow-brown, the transparency is 25 cm, and the water depth is 1.5 meters.

When stocking summer carp fingerlings, grass carp should be released first, and multiple species should be mixed and densely stocked, and the time of stocking silver carp should be controlled. On June 4, 9,300 summer carp with a size of 3.6 to 4.3 cm and a weight of 6 kg were released per mu; on June 26, 1,744 summer carp with a size of 3.3 cm and a weight of 0.45 kg were released; on June 30, 1,172 bighead carps with a size of 4.9 cm and a weight of 1.4 kg were released; on July 1, 2,585 silver carps with a size of 2.9 cm and a weight of 0.60 kg were released, with a total of 14,751 fish per mu and a total weight of 8.45 kg.

By the end of the year, the catch per acre was 1,504 and 1,193 grass carps weighing 75 grams and 165 grams respectively, weighing 310 kilograms; 1,167 crucian carps weighing 60 grams per tail, weighing 70 kilograms; 1,110 bighead carps weighing 70 grams per tail, weighing 78 kilograms; 2,074 silver carps weighing 100 grams per tail, weighing 207 kilograms; the average fish released per acre was 7,048, with a yield of 665 kilograms.

After the summer grass carp is put into the pond, it is fed with duckweed and duckweed. When the summer grass carp grows to 7 cm, it is fed with chopped tender grass. After 10 cm, it is fed directly with green grass. The feeding amount depends on the growth of the fish, feeding and weather conditions. It is fed less on rainy and hot days, and more on sunny days. The feed is generally controlled to be eaten 3 hours after the concentrated feed is fed, and the green feed is eaten 4 to 5 hours. 3260 kg of grass feed and 1260 kg of concentrated feed are used per mu.

Strengthen water quality management. Add new water once every 2-3 days in the early stage of breeding, with a water volume of 20-30 cm; from mid-July to early October, add water once a day, with a water volume of 25-30 cm. As the number of water injections increases, the water depth is maintained above 2.5 meters. After mid-October, add water according to the water quality. Water is usually added at 6 am in the morning, and at around 1 am in the middle of the breeding period.

Fish diseases are mainly prevented. In addition to thorough pond cleaning, pay attention to regulating water quality after summer flowers enter the pond. During the epidemic season of fish diseases, alternately sprinkle bleaching powder and quicklime every 7 to 10 days. For different fish diseases, use copper sulfate and ferrous sulfate mixture, rhubarb, trichlorfon and garlic to mix and feed.

Example 2: The pond area is 6.1 mu, with a water depth of 2.5 meters and water pumps for irrigation and drainage. The stocking of fish per mu is 5,000 grass carp summer flowers on July 2, 6,000 bream summer flowers on June 11, 3,000 crucian carp summer flowers on June 27, and 3,000 silver carp and bighead carp summer flowers on July 15. The average yield per mu by the end of the year is 611.15 kg. Among them, there are 1085 grass carp with a weight of 100 grams per tail, weighing 108.6 kg; 5372 bream with a weight of 31.25 grams per tail, weighing 167.85 kg; 1946 crucian carp with a weight of 41.7 grams per tail, weighing 81.065 kg; 2029 silver carp and bighead carp with a weight of 122 grams per tail/253.5 kg.

Feeding method: Use poultry and livestock manure to cultivate water quality 10 days before summer flower fish are put into the pond, and the water level in the pond is about 1 meter. Summer flower fish are stocked in uniform specifications, and 3-4% salt water is used to soak the fish for 5-10 minutes when they are put into the pond. When stocking, first put the main grass carp and bream, and stock crucian carp and silver carp and bighead carp in time. After stocking, gradually add water to deepen the water level. In late July, the water quality is easy to deteriorate. Frequently pump out the bottom water and inject new water, and make full use of the aerator to increase oxygen. In July, August, and September, use 20-30PPm lime water to adjust the water quality once every 15-20 days, and use it alternately with phosphate fertilizer to keep the water quality stable and weakly alkaline. Feeding is a combination of fine and green feed. Feed the fine feed quantitatively, and add 1% salt; feed the green feed to adapt to the palatable green feed and meet the needs as much as possible. In July, August, and September, feed well, feed well, and feed evenly, accounting for about 60-70% of the feed amount. The amount of concentrated feed fed should be increased or decreased according to the weather and feeding conditions.

Do a good job in fish disease prevention and control. Before the beginning of autumn, in addition to routine disease prevention, mix 6 grams of furazolidone per 100 kilograms with the daily feeding amount to make pellet feed and feed it. Three days is a course of treatment, and it should be done once a month; or mix 1% bleaching powder extract into the feed and feed it.

Fish farming

The appropriate size of a pond for adult fish breeding is 4 to 10 mu; the water depth should be about 2.5 meters; there should be good water inlet and outlet conditions, and it is best to have fast drainage and filling; an aerator with a capacity of 0.25 to 0.50 kilowatts should be installed per mu.

The main fish for stocking should be herbivorous fish (grass carp or bream), which can make full use of green fodder resources. The matching fish should focus on crucian carp, and other fish should be taken into consideration. The use of intercropping method can improve the utilization rate of ponds and increase economic benefits.

The goal of water quality management is to make the water thick in spring and autumn and thin in summer and autumn. The control of the main water quality indicators focuses on solving the three main lines of dissolved oxygen, non-ionized nitrogen, and carbon dioxide balance system. In winter, organic fertilizers and supplementary phosphate fertilizers are applied; in high temperature seasons, organic fertilizers are not applied. Reasonable use of aerators, water supplementation, quicklime, bleaching powder and other technical measures to improve water quality are adopted.

It is better to choose a combination of grass and bream feed. If a single feed is used, a plant feed with a high protein content should be used, and it should be combined with concentrated feed and green feed. The total amount of feed should be calculated based on the growth rate, survival rate index and overall weight gain of the fish, and the feed coefficient, and then it is better to feed it daily according to the allocation for 5 days. And it can be increased or decreased as appropriate according to the weather, feeding conditions, etc.

Prevention is the main approach to fish diseases, combining prevention with treatment.

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

Example 1:

The breeding results are 500 kg per mu with grass carp and bream as the main fish.

Pond 5.2 acres.

The average stocking rate of fish species is 55 grass carps weighing 568g/tail, 160 grass carps weighing 29g/tail, 100 bream weighing 150g/tail, 600 bream weighing 14g/tail, 50 carps weighing 50g/tail, 300 summer carps, 200 crucians weighing 52g/tail, 40 silver carps weighing 346g/tail, 260 silver carps weighing 77g/tail, 16 bighead carps weighing 392g/tail, and 50 bighead carps weighing 50g/tail. A total of 1,831 fish were stocked per mu, weighing 115.9kg.

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

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

Example 2:

Area: 9.1 acres

The average number of fish stocked per mu is 126 grass carps weighing 417g/tail, 358 grass carps weighing 10g/tail, 88 bream weighing 71g/tail, 210 bream weighing 13g/tail, 40 carps weighing 125g/tail, 145 carps weighing 24g/tail, 430 crucians weighing 34g/tail, 335 silver carps weighing 59g/tail, and 72 bighead carps weighing 69g/tail. The total number of fish stocked per mu is 113 kg.

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

The above example must be equipped with an aerator and good water inlet and outlet facilities due to the high fish loading capacity. In terms of feeding management, it is mainly fed with concentrated feed and green feed, and the amount of fertilizer is relatively small.

Fish disease prevention

1. Bleeding disease:

It is a viral fish disease. The fish's body surface is generally dark with a slight red tint, 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, gill covers, and fin ray bases.

Prevention and control methods: Injection of fish with inactivated vaccines can be preventive. For every 50 kg of fish, use 4-5 kg ​​of peanuts, 0.25 kg of garlic and salt to make a slurry, mix with 1.5 kg of bran to make a bait and feed it once a day for 5 consecutive days; at the same time, add 110 grams of copper sulfate to the pond with water for 0.33 meters per mu of water depth and sprinkle it for 5 consecutive days. For every 10,000 fish, grind 0.25-0.5 kg of rhubarb or liquidambar leaves into powder, boil or soak in hot water overnight, mix with feed and feed for 5 consecutive days. Apply copper sulfate, copper acetate, or copper chloride at a depth of 0.7PPm for two consecutive days.

2. Red skin disease: also known as hemorrhagic putrefactive disease.

Symptoms include partial or large bleeding on the fish's body surface, scales falling off, most obvious on the sides and abdomen of the fish, congestion at the base of some or all fin rays, slight rot at the end of the fin, and red patches often appear on the gill cover and the upper and lower jaws of the fish. Sick fish often swim alone on the surface of the water and move slowly.

Prevention and control methods: Prevent fish from getting sick or injured during fishing, transportation, and stocking. Soak fish in 5-10 ppm bleach solution for half an hour before stocking. Add sulfathiazole to the feed, with the dosage calculated as 1 gram per 10 kg of fish weight, and feed continuously for 6 days. For external disinfection, spray the entire pond with bleach.

3. Leukoderma: also known as white tail disease.

Symptoms are that at the beginning, small white spots appear at the base of the dorsal fin or on the caudal peduncle of the diseased fish, which quickly expand and make the skin behind the dorsal fin white, and the scales fall off, and the caudal fin rots and Saprolegnia occurs immediately, which can easily cause death. It often appears in the summer flower and fingerling stage.

Prevention and control methods: Avoid injury to the fish during operation. Before stocking, soak the fish in 2-3 PPm of mercuric nitrate for 2 hours; sick fish can also be soaked, which has a therapeutic effect. When the disease is serious, 1 PPm bleaching powder can be sprayed throughout the pond, with 1 gram of medicine per cubic meter.

4. Saprolegniasis:

The fungus invades the fish through wounds, parasitizes the epidermal tissue, and multiplies and spreads, forming cotton-like colonies on the surface of the fish, which are grayish white or light blue. It is easy to cause death.

Prevention and control methods: Before stocking, the fish pond should be thoroughly cleaned with quicklime to reduce pathogens. Be careful when operating to reduce damage to the fish. Sick fish can be soaked in 0.015PPm malachite green solution for 2 to 10 minutes.

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

It is caused by a large number of Ichthyophthirius multifida parasites, and small white dot-like vesicles appear on the gill cover of the fish. In severe cases, the fish's surface is covered with a white film, the mucus on the body increases, the fish is thin, swims slowly, and floats on the water.

Prevention and control methods: The fish pond 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 the small melon seed worms.

6. Anchor worm disease, also known as iron anchor worm disease and needle worm disease.

Anchorhead worms can be seen on the surface of the sick fish. The tissues around the worms become red, swollen, inflamed, and even ulcerated. The scales near the wounds are dissolved by the worm secretions and decay into gaps.

Prevention and control methods: Clean the fish pond thoroughly with quicklime to kill the larvae and eggs of anchorhead worms. Sick fish are strictly prohibited from entering the pond to cause infection. Soak the sick fish in a 1:50,000 (water temperature 15-20°C) or 1:100,000 (water temperature 21-30°C) potassium permanganate solution for 1.5-2 hours.

7. Bacterial gill rot

Symptoms include congestion of the inner wall of the gill bones, sometimes ulceration; rot of the gill filaments, white color, exposed cartilage at the tip of the gill filaments, and in severe cases, the edge of the gill flap rots into a ball and spreads to the entire gill flap. Sick fish often swim alone, move slowly, and have a black body color.

Prevention and control methods: When stocking fish, soak them in a 1:100,000 bleach solution for 30 minutes. Sprinkle the bleach all over the pond.

8. Intestinal inflammation

Symptoms include redness and swelling of the anus. In severe cases, blood or yellow mucus will flow out of the anus when the abdomen is gently pressed. Part or all of the intestines may become inflamed and appear purple-red.

Prevention and control methods: Add 10-15g of sulfamethoxazole to every 50kg of feed, make it into medicated bait and feed it once a day for 5-6 consecutive days.

1. Bacterial fish diseases: mainly include printing disease of silver carp and bighead carp and red skin disease of grass carp. These two diseases are caused by mechanical damage and bacterial invasion. The prevention and control method is: before the fish are put into the pond, soak them in 5% salt water for 3-5 minutes, and after they are put into the pond, use 1ppm bleaching powder (or 0.5ppm chloramine, 0.06ppm chloramine, 0.1ppm chloramine, 0.2ppm chloramine, 0.3ppm chloramine, 0.4ppm chloramine, 0.6ppm chloramine, 0.7ppm chloramine, 0.8ppm chloramine, 0.9ppm chloramine, 0.1ppm chloramine, 0.2ppm chloramine, 0.3ppm chloramine, 0.6ppm chloramine, 0.7ppm chloramine, 0.8ppm chloramine, 0.9ppm chloramine, 0.1ppm chloramine, 0.2ppm chloramine, 0.3ppm chloramine, 0.4ppm chloramine, 0.5ppm chloramine, 0.6ppm chloramine, 0.7ppm chloramine, 0.8ppm chloramine, 0.9 ...

To breed large-sized crucian carp, silver carp and bighead carp should be mixed, with silver carp accounting for about 20% of the main crucian carp and bighead carp accounting for about 10%. The stocking time of silver carp and bighead carp should not be too early, as it will affect the domestication of crucian carp.

Fish domestication Crucian carp is a fish that lives in the middle and lower layers of the water body. Fish ponds that mainly raise crucian carp must domesticate the fish, which is very beneficial to the growth of crucian carp. Five points should be noted during domestication: First, it is relatively easy to domesticate fish during the breeding stage; second, an appropriate amount 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 water level can be lowered during the domestication period to relatively increase the density, which is more conducive to domestication; fourth, silver carp and bighead carp should be released after the main crucian carp has formed the habit of floating up to grab food; fifth, during the domestication period, the pond water quality should be "thin" rather than "turbid and fat".

Feed particle size The particle size of feed for crucian carp should be "small rather than large". Crucian carp under 10 grams should choose feed with a particle size of 0.5 mm, 10-30 grams should choose 1 mm, 30-75 grams should choose 1.5 mm, 75-100 grams should choose 2 mm, 150-300 grams should choose 2.5 mm, and crucian carp above 300 grams should choose 3.2 mm.

The feeding rate of crucian carp breeding pond should be determined according to the size of crucian carp and the water temperature of the pond. When the water temperature is below 15℃, the feeding rate should be the lowest; when it is 16-23℃, crucian carp has a strong feeding ability and the feeding rate should be average; when the water temperature is 24-29℃, crucian carp has the strongest appetite, and the feeding rate should be the highest to ensure sufficient bait.

Disease prevention and control Hemorrhagic anchor disease is very harmful to crucian carp. The main characteristics are that crucian carp floats slowly and swims weakly, and the color is pale. Needle-shaped parasites can be seen on the abdomen and both sides of the back of the fish body. There are congested red spots the size of mung beans or peas where the parasites are attached. In the disease season, 0.3 grams of 90% crystal trichlorfon can be sprayed per cubic meter every half month for small-area main breeding ponds; for large-area crucian carp breeding ponds, trichlorfon can be used around the feeding area. Hang baskets (bags) 1-2 times a month, each time for 2 consecutive days, which has a good preventive effect. For the diseased pond, 0.5 grams of 90% crystal trichlorfon and 0.2 grams of ferrous sulfate mixture can be sprayed per cubic meter at one time, which has a better effect.

Can be mixed cultured, it takes 2-3 years for the fish to mature. It is best to release them in winter and spring