From the end of summer to the end of the year, the first-year fish species with a size of 12-15 cm and a weight of 30-40 g will be cultivated. The green and grass carp have a growth cycle of 3-4 years. In some places, the 1st instar fish species are reared into 500g 2nd instar fish species. 1. Fish ponds: In order to cultivate large-sized fish species, it is recommended to build special fish ponds with an area of ​​3-5 mu and a water depth of about 2 meters. The preparatory work for the summer fish species under the pond is the same as the fry pond. 2, stocking: There are two ways of single and polyculture. Generally used polyculture, mainly carp, carp 60%, grass carp 5%, carp 30%, carp 5%; carp-based, carp 60%, carp 10%, carp 20%, 10% of grass carp; mainly grass carp, 60% grass carp, 5% carp, 30% carp, 5% carp. 3, stocking density: depends on the bait, cultivation techniques, pond conditions, growth period and fish species out of pond specifications. Single stocking densities: If the summer stocks of 6000 per acre are bred, the culturing specifications will be 12-15 cm; if there are 9,000 stocks per acre, the culturing specifications will be 9-12 cm. Mixed density can be calculated proportionally. 4, daily management: (1) For ponds dominated by cockroaches or squid, basic fertilizer should be applied before stocking, timely dressing after stocking, and feeding a certain amount of grain bait; ponds mainly composed of grass carp and mackerel should be dominated by green fodder and appropriate amount of concentrate should be added. Ponds that use squid as the main source are fed grain pellets; ponds that are mainly used as herrings are treated with green manure or manure. (2) Adhere to the principle of "four observations" (see the season, see the sky, see the water, see the fish) and the "four prescriptions" (timing, quantitative, qualitative, and orientation). Early spring and late autumn and fall should be less investment, sunny days and more cast, less rainy days cast, heavy rain does not cast, water and fertilizer less cast, water thin and more cast, eating more and more investment, loss of appetite and less investment. Feeding 2 times a day, 1 in the afternoon and 1 in the afternoon, feed regularly. The feeding amount is relatively fixed and cannot be ignored. The bait is fresh and clean and the feeding should be fixed. (3) Daily management is the same as fry stocking. The food table must be sterilized to prevent fish disease. 5, and ponds and winter: early fall and winter, when the water temperature below 10 °C, according to the type of fish, specifications and pond classification. In northern China, where winter is long and the climate is cold, it is necessary to ensure safe wintering of fish species. Overwintering fishponds do not apply organic fertilizer after 8 months. Water quality is adjusted before icing. That is, 25% of the pond's old water is drained, new water is injected, inorganic fertilizer is applied, and 2-3 kg of urea is applied per mu. Water transparency is maintained. 30 cm. In winter, snow is cleaned in the area of ​​ice, which favors the transmission of sunlight. After icing, the water is changed by 20 centimeters per month. Bouffant Cap Machine,Bouffant Cap Making Machine,Disposable Cap Making Machine,Non Woven Shoe Cover Machine Dongguan Huitong Automatic Machinery Technology Co., Ltd , https://www.medicalmaskmachines.com