Measures for strengthening feeding and management to prevent and control fish diseases and increase domestic fish yield

1. Strict selection of parent fish: choose the natural original species, which requires good health and good gonadal development. Silver carp 6kg above, bighead carp 10kg above, herring 15kg above, grass carp above 8kg. The annual renewal rate of parent fish is about 10%.

Fish culture

2. Scientific cleaning of fish ponds: parent fish ponds. Irrigation and drainage is convenient, silver carp and bighead carp ponds have deep 20cm silt, green carp and grass carp ponds should contain no or less silt. It covers an area of 5 mu and has a water depth of about 1.5 meters. The pond should be cleared before stocking.

3. Rational stocking: 4 bighead carp and grass carp per mu were raised in ponds dominated by silver carp, 6-8 grass carps per mu in ponds with bighead carp, 3 carps per mu in ponds with silver carp and grass carp, and 5 silver carp (bighead carp) per mu in ponds with grass carp. The female-to-male ratio of silver carp, bighead carp, green carp and grass parent fish is generally 1: 1 / 1 / 5. At the same time, 10 mandarin fish and about 150 silver carp are released per mu to control the breeding of wild miscellaneous fish and large plankton.

4. Strengthen feeding and management: before stocking, the parent ponds of silver carp and bighead carp should put 500ml 700 kg mature organic fertilizer per mu to cultivate plankton, and fertilize properly after each mu. In addition, in sunny and warm weather, feed soybean cake milk to promote the gonadal development of fish. Herring parent fish are mainly fed with snails and clams, supplemented with bean cakes and other concentrate. Grass parent fish are mainly grass, ryegrass, potato vines, etc., supplemented by concentrate, if the grass is insufficient in spring and autumn, it needs to be based on concentrate. In order to keep the water quality fresh, the water should be injected frequently in autumn and the water depth should be kept above 1.5 meters in winter.

5. Pay attention to early labor: determination of the date of labor: after the weather turns warm, the lowest water temperature in the morning is above 18 ℃ for 3 consecutive days, and there is no strong cold air attack. Characteristics of mature parent fish: the abdomen of female fish is dilated, the reproductive pores are plump, soft and elastic on both sides, the reproductive pores are loose, the abdominal scales of grass carp are loosely arranged, the midline of the abdomen is concave, and the ovaries fall down, which seems to be mobile, and the effect of inducing labor is good. Male fish can squeeze out milky semen, which can be used if it is dispersed in the presence of water. In general, female fish are injected with 1000 international units of labor-inducing agent chorionic gonadotropin, or 40-50 micrograms of LRH-A per kilogram of body weight, while males are halved.

6. Optimize the hatching process: the water used for hatching should be filtered through a filter to prevent it from being mixed with floating objects and wild fish. Before each incubation, clean the incubator and incubator, provide appropriate water flow during the incubation period, and frequently turn the water body to check whether there are accumulated eggs in the bottom corner, clean it in time and maintain the water quality.

7. Comprehensive prevention and control of fish diseases: in parent fish cultivation, fish diseases are mainly prevented. 0.4ppm crystal trichlorfon is sprinkled in the whole pond in spring and autumn every year to prevent parasites. From April to October, 30ppm quicklime or 1ppm bleach is sprinkled in the whole pond to prevent bacterial diseases. Once the fish disease is found, actively prescribe the right medicine and cure it as soon as possible.