The growth of first-year grass carp fingerlings has a higher requirement for the environment of the water body, especially under the condition of intensive culture of ponds, the density of grass carp fingerlings is relatively high and it is very easy to develop. In order to obtain a high survival rate of aquaculture, it is necessary to grasp the prevention and treatment of fish diseases from every link in the aquaculture process and promote ecological farming and healthy breeding.
1. Clear pond disinfection. For ponds that cultivate grass carp fingerlings, dredging must be carried out. Generally, the bottom sludge should not exceed 15 cm in thickness. It is best to use quicklime to disinfect the water. The amount of quicklime is above 250kg/mu. Ponds that have had grass carp hemorrhage in the last breeding season are best not to use.
2. Disinfection of fish species. Try to release grass carp fingerlings with robust physique, consistent specifications, and reliable sources, but also use Povidone Iodine to soak fish species for 15 minutes to 20 minutes at the time of delivery. Conditional use can be made with special vaccines for grass carp.
3. Maintain a suitable culture density. Farmers can determine the appropriate density to be placed according to their actual breeding conditions. For those with good comprehensive conditions and higher aquaculture technology, the amount of grass carp summer flowers should be controlled at about 12,000 tail/mu; in general, the density should be controlled at about 8,000 tail/mu. In grass carp species-based farming models, squid should account for about 1/4 of the amount of grass carp. The release of large-sized squid is more conducive to improving the aquaculture water environment.
4. Improve the feed nutrition of grass carp fingerlings. Special feeds should be prepared based on the nutritional needs of grass carp fingerlings instead of catfish feed. Grass carp is a grass-eaten food for a long time and shows good utilization of plant protein feed. In the feed formulation of grass carp, vegetable protein feeds should be the main, supplemented by animal protein feed, and the ratio of the two versions should be 4 to 5:1. To prevent the phenomenon of excess nutrients during the growth of grass carp, the crude protein content of the pellet feed should be maintained at 28% to 30%. In the early stage of culture of grass carp fingerlings, the protein content of the feed may be higher, while in the middle and later stages of the culture, the protein content of the feed may be appropriately reduced. In the preparation of grass carp fingerlings feed, special premixes for grass carp should be used, with particular attention to the addition of choline chloride. In order to prevent the lack of vitamins, qualified persons can supplement by adding high-quality grass powder (such as lotus root powder, etc.). Green feed is rich in vitamins and minerals, and proper feeding can compensate for the lack of artificial compound feed, which is a very cost-effective method.
5. Control the feeding of pellet feed and timely supplement high-quality green feed. During the entire breeding process, according to the living habits and disease characteristics of grass carp species, the feed amount of compound feeds should be reasonably adjusted. After the fry is released, feeds with higher protein content should be fed in sufficient quantities. When the grass carp fish body reaches 6cm and enters the feeding conversion period, green feed such as duckweed is added in time. From the feeding period of grass carp fingerlings to the lunar period of the lunar calendar, for the high incidence of grass carp fingerling diseases, the feed amount of pellet feed should be strictly controlled. The frequency of daily feeding should be 2 times, and a variety of high quality water should be added appropriately. The amount of dry grass fed. After the white dew, the water temperature has decreased, and the high incidence period of grass carp fish disease has passed. This critical period should be sufficient to feed pelleted feed, and until the winter is stopped feeding.
6. Strengthen the regulation and management of water quality. Grass carp species prefer to live in a relatively fresh environment. Therefore, a variety of measures must be taken to improve the water quality during the cultivation process. In the early period of cultivation, new water should be added regularly; in the middle and later stages of breeding, as the load of fish in the pond increases, it is necessary to start the aeration machine to increase oxygen and keep the dissolved oxygen content of the water at 5mg/L or more; after 8 months, with With the increase of feeding quantity, the water quality gradually becomes fattened. Regularly sprinkling of photosynthetic bacteria, nitrifying bacteria, Bacillus and other microecological preparations and appropriate water exchange methods are used to regulate water quality, reduce organic matter content, and control the ammonia nitrogen content in the water at 0.1 mg. Below /L, the nitrite content is below 0.02mg/L, and the transparency of water is above 25cm.
7. Improve disease prevention measures and use drugs scientifically. After the grass carp was fed for 1 day to 2 days, chlorine dioxide was disinfected with water in time. From June to July, Quanchipa sprayed insecticide once or twice to kill parasites. Alternately use quicklime and chlorine dioxide to sterilize the water once every two weeks. For feeding green feed, use chlorine dioxide at a concentration of 1ppm to 2ppm for thorough disinfection. In view of the high incidence of hepatobiliary diseases during the cultivation of grass carp fingerlings in the western part of Henan Province, after July, Chinese herbal medicine baits consisting of Coptis, Phellodendron amurense, Astragalus membranaceus, Radix Isatidis, Capillaris henryi, and licorice should be fed and supplemented. Protect the liver and protect the liver with drugs such as Vc and VE, and feed it once every other month for 3 days to 5 days. In the breeding process, we must strengthen daily management and find timely treatment of diseases. During the middle and late breeding period, check the internal organs of liver, gallbladder and kidney every 10 days to prevent the occurrence of lesions. When treating illness, he tried to treat the disease symptomatically and prevent drug abuse.
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