2. Bighead Carp: People call this kind of fish chubby-headed fish, which lives in the middle and upper waters and mainly eats zooplankton. The breeding density is about 50 fish per mu.
3. Grass carp: it mainly lives in the middle and lower waters, and is discharged by vegetation in the water, and then eaten after the discharged feces produce microorganisms. When eating, the microorganisms inside will be filtered out, and the breeding density is about 0/200 per mu/kloc.
4. Black herring: Living in the lower waters, it mainly eats mollusks such as snails and mussels, and the breeding density is about 300 per mu.
5, control the timing of fish. The four major fish breeding modes are generally by stocking large-scale fish species and shortening the breeding cycle appropriately, so that good benefits can be obtained when the fish is listed in the peak season of consumption. If the market is not good, the profit space will be greatly reduced.
6. The local market demand should be taken into account in fish farming. Generally, when grass carp is cultured in the early stage, crucian carp can be selected for fish farming, and two different kinds of fish can be produced in one year, which not only speeds up the capital turnover, but also balances the risk of market fluctuation.
7. When fish reach the market specification, it must be listed. When the fish is cultured to a certain specification, it must be listed in time. In the actual breeding process, if the specification is enough, it will not be listed in the pond, which will affect the growth of small fish with specifications. Therefore, when breeding, as long as the market is not too bad, the fish should be listed when it is out.
8. Water transfer to improve the bottom. When cultivating four major fish, the bottom is changed at the peak of feeding in summer, once a week. Nitrogen fertilizer is generally used for water transfer, and microbial agents can also be used.
9. Prevention and control of fish diseases The prevention of grass carp diseases can be taken orally with probiotics. Early use of Astragalus polysaccharide and Gan 'an Likang powder can prevent and control diseases, and adding probiotics to feed can promote digestion and absorption.