The latest scientific black fish culture technology

When it comes to blackfish, we have to talk about its fresh and tender meat and nutritional value, and it is now extremely popular with consumers. therefore, when many people see the popularity of blackfish, they have the idea of cultivating blackfish. after all, there are not many farmers who breed black fish in large numbers, so they are not very competitive.

The latest scientific black fish culture technology

Black fish has strong adaptability to the environment, low requirements for pond water quality, and can be farmed with high density. 8000 million fish can be released in each mu of pond, and the yield can reach 4000 million kilograms. Black fish can grow fast, and commercial fish can be developed in early spring. Blackfish has less disease, high survival rate, simple transportation of adult fish, and convenient for long-distance sales.

1. Parent fish selection: the breeding season of black fish is in the middle of May every year. Mature and robust female and male black fish should be selected with the ratio of 1 ∶ 1 as parent fish. The method of distinguishing between male and female is that the abdomen of female black fish is dilated and soft, showing black and white, the outline of ovary is obvious, there are grooves in the center, and the reproductive foramen protrudes protruding, showing pink; the body color of male black fish is purplish red, there are small transparent white round spots arranged neatly from the bottom up on the dorsal fin, the abdomen is dark, the reproductive foramen is slightly enlarged, slightly concave, triangular, light pink. Before spawning, put the male and female fish in the cage for a day, do not feed, this is more conducive to spawning.

2.Parturition induction of parent fish: the female fish was injected twice, the first injection was the full dose of 1 stroke 3, the interval of 18 hours was 26 hours, and the remaining dose was injected once. The male fish dose was half of the female fish, and the female fish was injected with the second injection. Most of the fish are injected into the thoracic cavity, which is 45 °with the fish body, and the depth of the needle is about 1 centimeter. the commonly used hormones are common carp and crucian carp pituitary gland, with a dose of 480 / kg for females, which is halved by males, or chorionic gonadotropin, 16000-24000 IU / kg for females and halved for males.

3. Hatching of fish eggs

① artificial simulated natural environment hatching: after injection of oxytocin, males and females were put into the pool according to the ratio of 1 ∶ 1, so that they could spawn, fertilize and hatch naturally. After the fry are hatched, they are allowed to take care of them freely by making use of the protective habits of black fish. This method saves labor and time, but its disadvantage is that the survival rate of fish fry is low and the growth and development is inconsistent.

② artificial cage hatching: after injection to induce spawning, the male and female were placed in a cage of 4 to 6 meters in a ratio of 1 ∶ 1 to lay eggs and fertilized. After that, the parent fish were fished out and put into the pond. The fish eggs were placed in a 40-mesh cage with 10,000 fertilized eggs in each box and hatched by micro-running water. The hatching rate depends on the fertilization rate and water quality. 22-27 ℃, 32-48 hours, regular examination, timely removal of unfertilized eggs.

4. Seedling cultivation: before coming out of the film to 2cm, it should be raised in a cage of 1m × 0.5m × 0.5m made of 40 mesh cloth with a density of 2000 tails / m 2. After 4 days of emergence, rotifers, Cladocera, copepods, etc., were fed with a small number of times, once every 4 hours for 3 to 4 days. After that, the number of feeding increased, the times decreased, and gradually transitioned to 2 times a day. When the black fish fry reaches 2 cm, it is replaced by a cage made of summer flower net cloth with an area of 10 m 15 m 2, with a density of 500 m 600 pieces / m.

5. Feeding: zooplankton is the main food. At 4cm, add zooplankton to the fish paste. In order to prevent dirt and filamentous algae from blocking the mesh, scrub once a day, change the box once a week, and thoroughly disinfect the cage.

Feeding characteristics of black fish

Fierce carnivorous fish, and more gluttonous. The prey varies with the size of the fish. Seedlings less than 3 cm in length

The larvae less than 3 cm in length feed on aquatic insect larvae, tadpoles, shrimp and larvae, while adults over 20 cm in length feed on a variety of small fishes and frogs (small fish mainly refer to crucian carp, meal strips, red-eyed trout, Loach and various juvenile fish). The swimming speed of black fish is slow [2], but predation generally does not chase prey. Instead, they hide in the vicinity of aquatic plants or other hidden objects, and pay close attention to the movement around them. Once they find fish and other palatable live baits passing by, they will quickly attack and catch them in one fell swoop. Black fish eat a large amount of food and can often swallow live baits about half their body length, and the maximum capacity of their stomach can reach about 60% of their body weight. According to anatomy, a 500-gram black fish swallowed 8 grass carp with a length of 10 centimeters in a relatively short time. Blackfish also have the habit of killing each other and can swallow individuals of the same kind whose body length is less than 2/3. The amount of food intake is closely related to the water temperature. In summer, when the water temperature is high, it is quite gluttonous, and the food intake is large; when the water temperature is lower than 12 ℃, it will stop eating. Under the condition of artificial feeding, when the animal feed is insufficient, we can also feed on artificial compound feed such as bean cake, vegetable cake, fish meal and so on.

The reproduction of black fish

The spawning season varies with different climatic conditions. In South China, it is from mid-April to mid-September, with the peak in May and June, while in the central region, it is from May to July, and it is more concentrated in June. The breeding water temperature is 18: 30 ℃, and the optimum water temperature is 20: 25 ℃.

The age of sexual maturity varies slightly in different regions. In South China, the gonads of winter fish, which are usually more than 20 cm in length, have matured, while in the Yangtze River basin, it takes 2 winter seasons and a body length of 30 cm to spawn. Ophiocephalus Argus can reproduce naturally in ponds, ditches and reservoirs, and spawning grounds are generally distributed in shallow water areas with lush water plants. The number of eggs and the number of eggs laid are related to the size of the parent. The number of eggs laid by snakehead is usually about 20 ~ 30 000 eggs per kilogram body weight, the number of eggs laid by snakehead snakehead with a weight of 0.5 kg is generally 0.8 ~ 10 000 eggs, and some of them can reach 11 ~ 12000 eggs. The way of spawning is to build nests. Before spawning, sexually mature female and male parent fish swim in pairs on the spawning ground, using mouth to control water plants, plant fragments and spitting foam to build a slightly circular nest with a diameter of about 0.5 million meters and floating on the surface of the water. After the nest is built, before sunrise in the calm morning, the female and male fish chase each other and are in estrus. Then the female fish approaches the surface of the water under the nest, lies on its back on its abdomen, slowly shakes its body and lays eggs on the nest. At the same time, the male ejaculates here in the same posture.

Prevention and treatment of black fish disease

The prevention and treatment of black fish diseases should be based on prevention, and the water body should be disinfected regularly during the whole culture period. The fish were disinfected once a month after they were put into the pond, and then once every other month. Disinfection drugs are: dibromohydantoin, chlorine dioxide, quicklime, bleach, etc., the dosage depends on the water quality and drug instructions. Regular addition of vitamins, allicin and Sanhuang powder to the diet will help to enhance the physique and disease resistance of black fish. During the breeding period, more attention should be paid to observation, and effective prevention and control measures should be taken in time when the epidemic situation is found.

Now, no matter what it is, it is risky, and we should try our best to raise them and raise them. When using black fish culture, the cost is actually relatively large, so in the process of breeding, we should pay special attention to the prevention and control of black fish diseases, otherwise poor management will lead to economic losses, then the loss will outweigh the gain.