Parent fish cultivation techniques of four major domestic fish in spring

Spring is an important period for sexual maturity of parent fish. From the beginning of spring to spawning, a large number of nutrients in the parent fish are transferred to gonad development, so it is necessary to strengthen the cultivation of parent fish in spring to meet the needs of gonad development and promote the timely maturity of parent fish and smooth spawning. Its cultivation techniques are:

1. Early separation of ponds. Adjusting stocking density and species combination is the first condition for breeding parent fish well. The suitable pond area for parent fish separation is 2000~2600 square meters. Drain the pond water before dividing the pond, remove wild fish, snails and harmful organisms, remove part of sludge at the same time, and sprinkle 100~ 150kg quicklime per mu for disinfection. After 5 days, water was injected into the water at a depth of 1 meter. Fermented pig manure was applied to the parent fish of silver carp and bighead carp at a rate of 200~300 kg/mu as base fertilizer, and the stocking density was 150~200 kg/mu. Brood fish pond should not be set breeding fish and commercial fish. If the previous autumn has been divided according to the appropriate density of the pond, spring can no longer be divided. Such a fish pond can pump 1/3 of the pool water, keep the water depth at 0.8~1 meter, and dry the water for about 10 days, which can increase the temperature of the pool water and promote the parent fish to eat early.

2. Feed fertilizer early. After overwintering for 150 days, the parent fish has consumed a large amount of accumulated nutrients in its body and its constitution is weak. Whether it can supply sufficient nutrients at this time will directly affect the gonad development of the fish. Early application of bait and fertilizer can meet the nutritional needs of parent fish, promote gonad development of parent fish, increase egg yield and enter normal parturition period in due time. When the water temperature reaches 6~8℃, the brood pond of silver carp and bighead carp should be fertilized to promote the reproduction and growth of food organisms, and topdressing should be timely according to the water color. After the water temperature reaches 12~15℃, it is necessary to adhere to the "three looks" fertilization, that is,"look at the color of the water, look at the weather, look at the activities of the fish" fertilization, adhere to a small amount, multiple fertilization. The transparency of the pool water should be maintained at 25~30 cm. The parent fish of silver carp and bighead carp were mainly fed with fertilizer and water, and each parent fish was fed with about 20 grams of concentrated feed every day, such as bran, corn flour and bean cake powder, which accounted for one third respectively. In the early stage of cultivation, grass carp parent fish are fed with malt of 1 cm long, calculated by 25 g dry weight per tail per day, and fed with vegetable leaves and aquatic plants at the same time. In the later stage, forage is mainly used, and how much is eaten is thrown, and the degree is 3~4 hours.

3. Timely injection of water. Ensuring good water quality is the key to breeding parent fish. Flushing frequently and frequently can regulate water quality, improve water environment and promote gonad maturation of parent fish. Starting from the water temperature of 10℃, water should be flushed once a day, and the water level should be increased by 3~5 cm each time. The brood pond of silver carp and bighead carp should be flushed once a week; half a month before labor, the grass carp should be flushed once a day for 2 hours each time, and the pond of silver carp and bighead carp should be flushed once every 2~3 days. After reaching the highest water level, fresh water should be pumped.