Aquaculture Tips: how to effectively prevent Grass Carp Disease in Autumn

First, improve the disease resistance of fish through a variety of ways.

① improved varieties: new varieties with strong disease resistance, fast growth, high survival rate, delicious meat and good shape were cultivated by crossing, especially by mating and generation selection of excellent grass carp from different river systems.

② popularizes artificial immune technology to improve the immune protection of fish.

③ improves the operation method and removes parasites, snakes, rats, birds and other enemies, prevents fish from abrasions and bites, and protects the immune barrier of fish, thus improving the immunity of fish.

④ implements scientific fish culture to make grass carp eat well in excellent waters and improve disease resistance, that is, ecological disease prevention method is adopted. The first is to reform the feeding system and method of cultivating grass carp fingerling, changing the one-time sub-pond to two or more times, so as to make the density of water and fry more reasonable, promote fast growth and improve disease resistance, and change dense culture to sparse culture and seedling stocking density. In the past, there were 20 ~ 300000 in primary ponds, 20 ~ 30 000 in secondary ponds, 10 ~ 150000 in primary ponds, 1 ~ 15000 in secondary ponds and 3000 million in tertiary ponds. Change the mixed culture of fish species into coarse and fine fish species, classified breeding to prevent the polarization of fish species; in the late stage of breeding (that is, three-stage pond breeding), it has changed from fertilizer-water breeding to thin-water breeding, because the fish species have reached about 6cm. The feeding habits have changed from zooplankton to green feed, and the natural habits have also changed, so there is no need for fattening and topdressing in the third-level pond water. Second, do a good job in the scientific formula of feed and adhere to the "four fixed" feeding, in order to prevent nutrition deficiency. Grass carp fed with compound feed should be fed with appropriate amount of green fodder and vitamins to facilitate the rapid growth of grass carp.

Second, do everything possible to eliminate pathogens and their mediators. Mainly adhere to the "second diligence", that is, frequently patrol the pond, frequently remove pathogens and their mediators and "Qixiao": water source disinfection, fish pond disinfection, manure disinfection, fish seed disinfection, feed disinfection, food farm disinfection, tool disinfection.

Third, according to the requirements of each growth stage of grass carp, create a good environment to facilitate the safe, healthy and rapid growth of grass carp. Grass carp species in the initial stage of breeding (body length less than 7 cm), the food is mainly zooplankton, the water quality is fat and cool (transparency 25cm to 35cm). In the middle and later period, the diet was completely transformed, mainly green fodder, requiring the water quality to be lively and cool (more than 40 cm transparency). Therefore, in order to make grass carp grow well, the initial stage must be reasonable to improve the water quality (including base fertilizer and topdressing) and appropriate algae water to make the water quality fat and cool. In the middle and later stages, it is not only not fattening, but also reasonable combination of chain, bighead carp and other filter-feeding fish to lose weight and often pour water into the pond or turn on the aerator to increase oxygen, so as to make the water quality live and cool. In addition, the water quality is required to be slightly alkaline (ph value 7.5-8.5).