Feeding of grass silver carp and bighead carp in autumn and winter

The breeding of parent fish is an important link in the artificial reproduction of green, grass, silver carp and bighead carp. The feeding and management in autumn and winter directly affects the effect of spawning in the second year, so full attention must be paid to it.

1. Conditions and cleaning of fish ponds.

The fish ponds for breeding parent fish should not only be close to the spawning pond but also have good water source conditions, and it is convenient for irrigation and drainage. The bottom of the pond is less silt, silver carp and bighead carp ponds with a depth of 20 centimeters is enough, green and grass carp ponds should contain little or no silt. The area is 2000,3300 square meters and the water depth is about 1.5 meters. Parent fish culture ponds should be cleaned before stocking, dredging excessive silt, repairing ridges, cutting weeds, and thoroughly cleaning the ponds with drugs such as quicklime or bleach.

two。 The stocking of parent fish.

(1) time: the stocking of parent fish should be completed by the end of October and no later than February of the following year at the latest. Parent fish used for breeding are best cultivated locally, or they can be collected from rivers, lakes, reservoirs and other waters. The collection of adult fish can be carried out from November to December, because the water temperature is lower, the fishing and transportation of parent fish are not easy to be injured, the survival rate is high, and stocking is not easy to die. In addition, earlier fishing can have a longer period of time to restore the physique, after the beginning of spring can be normal development, catch up with reproduction.

(2) density: reasonable stocking density is an important condition for parent fish cultivation. The ponds dominated by silver carp and bighead carp are stocked with about 100,150 kilograms per mu. In the ponds where silver carp are mainly raised, there are 1620 silver carp with a tail weight of 6kg per mu, 2 bighead carp with a tail weight of 10 kg and 3 grass carp with a tail weight of 10 kg. The ponds that mainly raise bighead carp generally do not raise silver carp, lest silver carp affect bighead carp. 4 grass carp with a tail weight of 6 kilograms per mu are reared. The female-to-male ratio of silver carp and bighead carp is generally 1. 5. If there are fewer males, the ratio can be slightly lower, but not less than 1:1. Silver carp and bighead carp should not be planted in the parent fish ponds, so as not to affect the gonadal development of the parent fish. In ponds dominated by grass carp, the stocking capacity is about 130-150 kg per mu, that is, 12-15 grass carp with a tail weight of 7-10 kg and 2-3 parent fish of silver carp or bighead carp. The pond dominated by herring has a stocking capacity of 160-200 kg per mu, that is, 8-10 herring with a tail weight of 15-20 kg. The female-to-male ratio of green and grass parent fish is 1. 5.

3. Feeding and management of parent fish.

(1) Silver carp and bighead carp: silver carp and bighead carp mainly feed on plankton and should be fertilized properly to cultivate plankton. Fertilization in autumn is the key to raising parent fish of silver carp and bighead carp. It is necessary to master the water quality and ensure the "fat" and "cool" of the pond water. Generally speaking, 500-750 kg organic fertilizer per mu should be used as base fertilizer before parent fish stocking, and then topdressing should be carried out according to the principles of less application, diligent application and water fertilization. In principle, 350-400 kg per month. Fertilization should be applied as appropriate after the beginning of winter to ensure that the water color does not change in winter. In the sunny and warm weather in winter, concentrate such as soybean cakes and soy milk should be fed. At this stage, new water should be injected appropriately according to the situation, in order to adjust the water quality, mainly green fodder, the combination of green and fine feed: regular water injection is the key to cultivate grass carp. The green materials of grass carp in this period can be made of grass, ryegrass, sweet potato vines and so on. Concentrate can be used for large grass carp, malt, bean cake, etc.: the feeding amount depends on the feeding condition of the parent fish. The green feed can be up to 30% of the fish body weight, and the concentrate feed is 1%-2% of the fish body weight. As the temperature drops, the green feed gradually dries up, and the feeding intensity of grass carp decreases. At this time, all concentrate should be used: it can be fed every other day when the water temperature is high, and once every 5 days when the water temperature is low. In this way, the parent fish are fed until they stop eating during the winter. Concentrate should be put on the table, which should be set up at the bottom near the shore, and the table should be cleaned regularly; the green material should be put into the straw basket, and the straw basket should be moved regularly to remove the sunken rotten grass. During this period, water should also be injected regularly to keep the water quality fresh, usually once every half month to one month.

(2) herring: at this stage, the herring should be mainly fed with snails and clams, and when the quantity is insufficient, it should be supplemented with bean cakes and other concentrate. Snails, clams, etc., should be evenly scattered on a flat beach with a water depth of 0.6 million meters and 2 meters away from the pond bank. The amount of feeding depends on the feeding condition, depending on the degree of satiety. It is necessary to ensure that the snails, clams and the right amount of concentrate are fed to the fish throughout the year, so as to ensure the gonadal maturity of the parent fish. Herring ponds also need fresh water, so new water should be injected regularly to promote the appetite and gonadal development of parent turtles, but the frequency of water injection can be slightly less than that of grass carp.