Culture techniques of grass carp

Grass carp local name mix, carp, grass green and so on. Grass carp have extended body shape, slightly subcylindrical trunk, flattened tail, no ventral ribs, medium-sized head, wide and flat snout, curved mouth and slightly protruding maxilla. The Gill rake is short and rod-shaped and sparsely arranged. The hypopharyngeal teeth are comb-shaped pectinate teeth with large and round scales. The lateral line is slightly curved and extends back to the middle of the caudal stalk, the dorsal fin has no hard spines, the starting point is opposite to the ventral fin, and the distance from the rostrum is slightly farther from the caudal fin base. The anal fin has no hard thorns, and the starting point is closer to the base of the abdomen than to the base of the caudal fin. The fish is tea-yellow, the back is bluish gray, the abdomen is gray, the pectoral and caudal fins are grayish yellow, and the other fins are lighter. Grass carp look like herring, but their body colors are different. Grass carp body color tea yellow with gray, even fin gray yellow, while the black carp body color is bluish black, even fin in the white belly set off more bluish black.

Grass carp (Ctenopharyngodon idellus) is widely distributed in China, except for the natural distribution in China and the Qinghai-Tibet Plateau, but also in all major river systems. Grass carp generally live in the middle and lower layers, and sometimes look for food in the upper layer. Active in sex and fast in swimming. Herbivorous, the fish period is dominated by plankton, and the young fish also feed on aquatic insects. Juvenile fish with a length of more than 50 mm. Gradually become herbivorous; the body length is about 100 mm, which is fully adapted to feed on aquatic higher plants. Adult fish mainly feed on higher aquatic plants, such as bitter grass, verticillium verticillata, small grass algae, Euphorbia angustifolia, duckweed, and Wuping; submerged grassland areas are often fattening places for grass carp, and some dry grasses are also favored by grass carp.

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

Artificial propagation

The new fish for grass carp breeding should choose the fish with strong physique, good shape, fast growth, no trauma and disease, which are over 4 years old and weighing more than 5 kilograms, and should be cultured in a parent fish pond with a depth of 1.5 to 2.5 meters and a depth of 2 million mu. It is suitable to breed parent fish 100kg to 125kg per mu, generally 6kg to 8kg grass carp to 15,27fish, and the ratio of female to male is 1 ∶ 1.5kg. It can raise 5 million silver carp and 1 bighead carp, snail and 3 herring in the pond for a long time. The cultivation of parent fish should be strengthened, especially in spring (from March to spawning). Green feed should be given priority to. Appropriate feeding concentrate, can feed lettuce leaves, package leaves, etc., can be used to feed grain sprouts or malts. Infuse new water every 5-7 days, adding 3-6 cm each time, 1-2 weeks before delivery, once every other day to strengthen running water to stimulate gonadal development and maturity. Mature parent fish, gently press the abdomen, the reproductive pore can squeeze out eggs or semen. Mature parent fish can be injected with stimulating agents such as pituitary, chorionic gonadotropin, luteinizing hormone-releasing hormone and analogues to promote oestrus and lay eggs naturally in the spawning pool or by artificial insemination. The fertilized eggs collected can be hatched in running water in an hatching container, and the hatching density increases or decreases with different containers, usually releasing 1 million eggs per cubic meter. The membrane can be removed after about 20-32 hours (the detachment time varies with the water temperature). Generally, 3-5 days after removal, the yolk sac of the fry disappears, and the swim bladder can be inflated out of the hatching container.

Fish fry cultivation

Fry culture refers to the fry after about 20 days to cultivate into about 3 centimeters of summer flower fish, commonly known as "hair pond". The fish fry culture pond area is 1 mu, the pond depth is 1.5 meters, the water depth is 1.5 meters, the pool shape is rectangular, the drainage is convenient, and the loam is the best at the bottom. Fish fry ponds should be cleaned and disinfected in the following ways:

1. Quicklime: the fish pond with water depth of about 1 meter per mu needs about 130 kilograms of quicklime to clear the pond. If the pond water is drained, it only needs 50 kilograms and 80 kilograms per mu. When the quicklime water melts and does not cool, the whole pool can be sprinkled immediately. After clearing the pond for 7 days, you can put in the fish fry. In addition to pond cleaning and disinfection, quicklime can play a role in regulating water quality and fertilization. Therefore, quicklime is widely used to clear ponds.

2. Bleach: for fish ponds with a water depth of 1 meter per mu, about 14 kg of bleach is used. If the water depth is 5 cm to 10 cm, use 3 kg to 5 kg. Melt the bleach with water and sprinkle the leeward all over the pool. In case of scorching sun, the effect is better. Fish fry can be released 5-7 days after clearing the pond.

3. Ammonia: when the water depth of the fish pond is 10 cm, use more than 50 kg per mu. The dosage is often related to the storage time of ammonia. During the operation, the whole pool should be sprinkled in the leeward, such as in the scorching sun, the efficacy will be greater. Generally, water can be injected one day after ammonia application, and fish fry can be released after 3-5 days. The characteristic of this method is that the speed of cleaning and disinfection is fast, and the drug office disappears quickly.

4. Rotenone: when the water depth is 1 meter, about 1.3 kilograms of rotenone is used per mu of fish pond. The fish rattan essence sold in the market actually contains 2.5%, 5% and 7.5% EC. During the operation, add water 10 to 15 times (the effective depth is about 2PPm) and then sprinkle it in the whole pool. The seedlings can be released after clearing the pond for 7 days.

5. Tea meal: when the water depth is 1 meter per mu, use tea meal 35kg to 40kg. During the operation, first mash the tea cake into small pieces, put it in a water tank and soak it out for one day, then add a lot of water to dilute it, stir it well, and sprinkle it with dregs in the whole pool. The time of disappearance of toxicity was about 7 to 10 days.

6. Pentachlorophenol sodium, dimethyltetrachloride and prometryne mixture: when the pool water is about 13cm, use pentachlorophenol sodium (65% water-soluble powder) 1 kg per mu, dimethyltetrachloride (70% water-soluble powder) 75 grams, prometryne (50% wettable powder) 150 grams, mix them and dissolve them with water, sprinkle them evenly throughout the pool. Generally, water is added 10-15 days after application, and then base fertilizer is applied. After about 2-3 days, the water can be tested, and fish fry can be put into the pond when non-toxic.

7. Pentachlorophenol sodium: use 2 kg per mu of pond (water depth 0.5 m), soak the whole pond for 5-7 days, drain the water, spray it for 4-5 days, and then inject water.

8. Inject new water: the fry pond can be infused with fresh water after disinfection. When injecting water, filter it with sieve silk at the inlet, injecting water 40cm to 50cm. Basic fertilizer should be applied before the fry goes into the pond. Generally, it is better for the fry to go to the pond with medium fertilizer. That is, 3 to 5 days before fry stocking, 200 kilograms of animal dung per mu, or 50 kilograms of dung, 100 kilograms per mu. If you need to accelerate fertilizer and water, you can use inorganic fertilizers. Generally, ammonia is 5 kilograms per mu, and ammonium sulfate and ammonium nitrate are 2.5 kilograms per mu. Through the application of basic fertilizer, zooplankton and plants in the water grow rapidly, and the water color changes to light green or light brown, and then fish fry can be released and cultivated.

9. Stocking fish fry: fish fry should choose groups with neat size, fresh and tender body color, fat and symmetrical body, and swimming activities. Generally, 10-120000 grass carp fry are released per mu; if the area of the fish pond is large, 200000 fry can be released per mu. Fish fry feeding methods vary from place to place, including soybean milk feeding method, grass feeding method, pig manure feeding method and so on. Soybeans are mostly raised in this area. After the fish fry go into the pond, they should be fed soybean milk for the first time every 5-6 hours. If they go into the pond in the afternoon, they should be fed in the afternoon. Usually twice a day, 8: 9 a.m. and 14-15:00 p.m. No later than 16:00 at the latest. In the fish fry under the pond for 10 days, feed 1.52kg soybean per mu or 2kg 2.5kg soybean cake after soaking into the milk, 10 days later, according to the fat and thin water quality, appropriate increase or decrease, such as rain and low temperature should be added to the amount of soybean milk, soybean milk should be sprinkled evenly throughout the pond. If combined with fertilization, you can reduce the amount of bean cake or soybeans, generally can be fertilized 4-5 days after the fry is put into the pond.

Fresh water should be injected regularly during the fry culture. when the fry goes into the pond, the water is generally about 50 cm. 4-5 days after the fry goes into the pond, 10 cm of water should be added, and then every 3-4 days, the pond should reach about 1 meter. Adding new water should strictly prevent wild miscellaneous fish from mixing into the pond. Strengthen pond patrol to find problems and deal with them in a timely manner. If there is any leakage in the fish pond, it should be blocked in time. Timely removal of fertilizer dregs, soymilk foam on the water surface, keep the pool water environment clean, and do a good job in fish disease prevention. After 20-30 days of cultivation, the fry can generally grow to about 3 centimeters of summer flowers, which should be cultured in separate ponds. Before the summer flower fish come out of the pond, they should go through the second net-pulling exercise before they can come out of the pond. Generally, about 20 days after the fry go into the pond, close-eyed nets are used to catch fish in the pond. the time should be chosen at 8: 9 a.m. on a sunny day, and the fish will be put into the net at 8: 9 a.m. and put back to the original pond a few minutes later. After an interval of one day, the fish will be gathered into the net, the net will be lifted, all the fish will be dumped in the cage, and the cage will be dragged slowly to make the top water swim for 1 hour and 2 hours, and the fish will be put in the pond. After the second net-pulling exercise, the summer flower is physically strong and can be separated from the pool.

Fish culture

Grass carp fingerling is generally raised from summer flower fingerling to one-year-old fish of about 13.2 cm in the first year, which is also called larval mouth grass carp. In the second year, two-year-old grass carp fingerling, also known as old grass carp, are raised to 23.5 kilograms of adult fish.

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

1. Example 1

High-yield culture with larval mouth grass carp. The pond area is about 4 mu, the average water depth is about 2.5 meters, and it is convenient for drainage and irrigation. Thoroughly clear the pond with 75 kilograms of quicklime per mu according to party rules. One ton of fermented cow dung was applied per mu about 10 days before the summer flower fry went into the pond. When the summer flowers go down the pond, the water color is yellowish brown, the transparency is 25 cm, and the water depth is 1.5 meters.

In summer fish breeding, the main grass carp should be released first, multi-species mixed culture should be kept densely, and the stocking time of silver carp should be controlled. 9300 grass carp with 3.6cm to 4.3cm summer flower, weighing 6kg, 1744 crucian carp with summer flower weighing 0.45kg on June 26th, 1172 bighead carp with 4.9cm bighead carp weighing 1.4kg on June 30th, 2585 silver carp with a total weight of 0.60kg on July 1st, 14751 carps per mu with a total weight of 8.45kg.

At the end of the year, 1504 and 1193 grass carp fingerlings of 75g / mu and 165g / tail, weighing 310kg, 1167 crucian carp fingerling with weight of 70kg, 1110 bighead carp fingerling with weight of 78kg, 2074 silver carp fingerling with 207kg per mu, and 7048 fingerling per mu with an average yield of 665kg were caught.

After the summer grass carp goes into the pond, feed Wuping and duckweed. When the summer flower fish grows to 7 cm, feed the chopped tender grass instead. After 10 cm, feed the grass directly. The feeding amount depends on the fish growth, feeding and weather conditions. Feed less in rainy and sultry days and more in sunny days. Feed is generally controlled in 3 hours after concentrate feeding, and it is appropriate for green feed to be finished in 4-5 hours. 3260 kg of forage and 1260 kg of concentrate are used per mu.

The management of water quality should be strengthened by adding fresh water once every 2-3 days in the early stage of feeding, with a quantity of 20,30cm, and from mid-July to early October, once a day with a quantity of 25cm. With the increase of the number of water injection, the water depth is kept above 2.5 meters. After the middle of October, water will be added according to the water quality. When adding water, it is usually 6 o'clock in the morning, and about 1 pm in the middle of cultivation. Fish disease is mainly to prevent, in addition to thoroughly clear the pond, from the summer flowers into the pond, pay attention to the regulation of water quality. During the epidemic season of fish disease, bleach and quicklime are sprinkled alternately every 7 to 10 days. According to different fish diseases, the mixture of copper sulfate and ferrous sulfate, rhubarb, trichlorfon and garlic were used respectively.

2. Example 2

To grass, bream species-based culture pond area of 6.1 mu, water depth of 2.5 meters, irrigation and drainage by water pump. 5000 grass carp, 6000 snout bream, 3000 crucian carp and 3000 silver carp and bighead carp were released per mu on July 2, June 11, June 27 and July 15, respectively. By the end of the year, the average yield per mu was 611.15 kg. Among them, 1085 100g / tail grass fingerling, weighing 108.6 kg, 31.25g / tail bream fingerling 5372, weighing 167.85 kg, 41.7g / tail crucian carp fingerling, 81.065 kg, 122g / silver carp and bighead carp, 2029 / 253.5 kg.