Cultivation method of black fry 1 Pull the net and breed separately.
After about 3 weeks of cultivation, the fry are 2.5 ~ 3 cm long, and the difference between individuals is relatively increased, so the phenomenon of food weakness is more serious, especially in the case of insufficient feeding. By pulling the net, screening and feeding, appropriately reducing the breeding density and striving for the same size, we can avoid eating strong and eating weak. In sunny days, you should choose to feed separately, and the fry are not full when pulling the net, so you need to stop eating 1 day to pull the net. If the fish in the pond are floating, you can't pull the net, otherwise it will cause a lot of deaths. The pulling time is usually arranged after 8 ~ 9 am, and the pulling operation should be careful to prevent the fry from being injured. It is best to choose soft materials (vinylon thread, nylon thread) for weaving nets, and be sure to bring water when moving fry. After about 3 weeks of cultivation, the fry grow to more than 6 cm, becoming small-sized fish species, and can continue to cultivate large-sized fish species out of the pond. At this time, it is the end of June and the beginning of July, and the temperature and water temperature are relatively high. Also choose sunny days and fish at 7 ~ 10 in the morning. /kloc-After 0/0 hour, the water temperature continues to rise, which is not suitable for fishing. Be careful when fishing, move quickly, reduce the damage to the fish species, and stock them separately according to the size of the specifications.
2. Water quality management
With the fertilization, feeding and fry growth in aquaculture ponds, the water quality is easy to be overweight or even deteriorated, which affects the survival rate of fry. It is necessary to inject new water in time to adjust the water quality. General water injection 1 demand 1 week or so. When sowing, the water level is only 40 ~ 50 cm. In the early stage, water was added to raise the water level and dilute the water quality by 5 ~ 10 cm each time, and then 10 ~ 15 cm each time until the water depth was appropriate. Maintaining a certain amount of water can increase the activity space of fry, reduce the concentration of harmful substances in water, improve the chemical conditions in water and promote the growth of fry. Pay attention to adjust the fatness of the pool water in time when adding water, especially to prevent the pool water from being too fat. In the future, we will adopt the way of changing water while entering and leaving, strictly control the water quality, make fry grow healthily in a good ecological environment and improve the survival rate of fry.
Patrol the pond
Someone should patrol the pond regularly every day. This work is very important in daily management, which can find and solve problems in time. Generally, the pond is visited three times a day, especially in the morning and evening. In the morning, we should pay attention to whether the fry float. If so, we should pay attention to whether the water quality is too fat. According to the floating situation, we should take corresponding measures such as injecting new water to control it to prevent the fish from dying. If the fish fry are found to be seriously clustered during the night patrol, they should be dispersed or moved in time, especially in downward flow, which should be moved to upwind or other places. If the fry are found swimming back and forth along the edge of the pond during the day, it is a phenomenon that the fry are hungry, indicating that the feeding amount is insufficient and should be increased. Pay attention to the changes of water quality during the day, especially when the weather is hot, the water quality is fat and there are many algae. The water quality will be clear in the morning, green at noon, and a large number of water blooms (algae skins) will float on the water at night. It is necessary to change water properly, reduce fertilization and remove algae skin.
4. Survival rate of fry cultivation
According to the reports and statistics of snakehead fry propagation over the years, the survival rate of snakehead fry is generally 60% ~ 65% in the fry cultivation stage, that is, the fry with a total length of 3 ~ 4 cm is cultivated.
The key to the cultivation of snakehead fry is that when the snakehead fry just came out of the egg membrane, the individual development is still very incomplete, very delicate and difficult to manage, as shown in the following figure:
(1) The snakehead fry is easily affected by waves and currents. And the gauze is dead;
(2) Living in groups at night is prone to death due to lack of oxygen;
(3) There is no scale on the body surface, and it is easy to be injured, infected with water mold and attacked by protozoa (rotifer, small melon worm, oblique tube worm, etc.). );
(4) When dead eggs and dead seedlings rot, a large number of harmful substances and oil beads are released, which pollutes water quality and environment. Therefore, when cultured in cages or incubators, fry can only be replaced in large cages or cultured directly in ponds after their feeding activities are normal.
How does snakehead breed? The scientific name of snakehead is snakehead, commonly known as Hei Bang, dutiful son fish, God of Wealth fish, raw fish, snakehead and so on. It has the functions of clearing away heat and toxic materials, promoting fluid production to quench thirst, expelling toxin and promoting granulation, and is a nourishing treasure for the infirm.
Culturing snakehead has many advantages: snakehead has strong adaptability to the environment, low requirements for pond water quality, high culture density, high yield and high benefit; Black snakehead grows fast, and the fry propagated in early spring can develop into commercial fish in the same year; Snakehead has low incidence and high survival rate; The transportation of adult fish is simple and convenient for long-distance sales.
There are two ways to hatch fish eggs: one is to artificially simulate the natural environment, after injecting oxytocin into snakehead, put male and female fish in a pool according to the ratio of 1: 1 and let them naturally lay eggs, fertilize and hatch; The second is artificial caging.