How much is a Shenyang black fish fry at present? How to propagate artificially? What are the breeding techniques?

Black fish is a valuable freshwater fish, known as "the treasures of fish", also known as snakehead, raw fish, mullet, financial fish, match head fish, etc., is a kind of high-level health products with comprehensive nutrition and delicious meat, and has always been regarded as a nourishing treasure for those who recover from illness and those who are weak in old and juvenile bodies. At present, the benefit of black fish culture is remarkable, and it has become one of the most popular aquaculture. Except for plateau areas, black fish are mainly distributed in the Yangtze River basin and north to Heilongjiang, especially in Hubei, Jiangxi, Anhui, Henan, Liaoning and other provinces. So, how much is a Shenyang black fish fry at present? How to propagate artificially? What are the breeding techniques?

At present, the price of Shenyang black fish fry is about 1 yuan, and the unit price will be cheaper if the quantity is large.

Black fish has strong vitality and ranks first among freshwater fish. 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.

Artificial reproduction of black fish

1. Parent fish selection

The breeding season of black fish is in the middle of May every year, so 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. Brood fish to induce spawning

The female fish was injected twice, the first injection was the full dose of 1 stroke 3, the interval was 18 to 26 hours, and the remaining dose was injected once, and the male fish dose was half of that of the female fish, and the second injection was given to the female fish. 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 ind / m 2. After 4 days of film 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 transited 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. put in the bait

The main bait is zooplankton. 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.

Culture technology of black fish

1. Pond construction

Choose the east-west direction, rectangular pond, the bottom of the pond is soil, the depth of the pond is 2-2.5 meters, the water depth is 1.5-2 meters, the inlet and drainage should be equipped with anti-escape facilities, and 100kg / mu of quicklime should be thoroughly disinfected 15 days before breeding.

2. Fish restocking

Before entering the pond, the fish species should be soaked in 3% to 5% salt water for 10 minutes for 15 minutes, and then put into the pond. The fish species with a body length of 10 centimeters and 14 centimeters will be stocked with a stocking density of 9000 million fish per mu and 16 fish species per mu, with a stocking density of 8000 fish per mu.

3. Daily management

Pay attention to observe the feeding, activity, incidence trend and environmental changes of black fish. Change the water of the pond every week in spring, change every 3 days in high temperature season, change every 7 days, enter and drain to catch the escape net, and the ridge of the pond is more than 50 cm above the water surface. For the discharged sewage, the necessary sewage treatment should be carried out.

4. Feed feeding

The feed for feeding black fish includes artificial compound feed, small mixed fish of fresh water or sea water, and scraps of livestock and poultry after slaughtering. Before feeding, small miscellaneous fish need to be sorted to remove fish with hard spines, such as Pelteobagrus fulvidraco. Before feeding, use slapping as a signal to concentrate distant fish near the bait table to reduce feed waste. The initial feeding amount is 10% of body weight, and then it can be appropriately reduced to about 5% of body weight. It should be fed with one spoonful, so that the waste of feed is less. Feeding should adhere to the "four-fixed" principle, and each pond should choose 3-4 feeding points. The way of intensive culture is adopted, with a body length of more than 10 cm. After 8-9 months of culture, the survival rate is 75%-80%, the average body weight is 0.5-0.7 kg, and the yield per mu is 4000-5000 kg. Plant some aquatic plants in the pond, such as Rabdosia angustifolia, Sophora flavescens, water peanut, etc., and the planting area should be controlled at 1 / 3 of the pond area.