Experience of quality Control in Freshwater White Pomfret Culture

Colossus brachypomus (Colossus brachypomus) is a tropical and subtropical fish. It has the characteristics of wide feeding habits, fast growth, few diseases, easy fishing, delicious taste and rich nutrition. In recent years, the lack of scientific management and quality control in the breeding process has led to the decline of the quality of freshwater pomfret, the increase of physical and chemical costs and the low economic benefits. Through several years practice, the author thinks that the quality control of cultured freshwater pomfret should be carried out from the following aspects.

First, the pond culture conditions quality control of freshwater pomfret pond area requirements are not strict, the area of 5~15 acres is appropriate, pool depth of 1.5~2 meters, bottom flat, no excessive silt. Pond requirements sufficient water, good water quality, separate water supply and drainage system, no pollution sources around. Culture pond mouth was rectangular, east-west direction, no leakage. The pond should be equipped with an aerator. In winter, the pond must be cleaned and exposed to the sun until about April 15 of the second year, and the pond should be cleaned with quicklime. Dry pond cleaning, quicklime dosage per mu is 75 kg; wet pond cleaning, quicklime dosage per mu is 150 kg. 10-15 days before fingerling stocking, adjusting the pond depth to 1.2-1.3 meters, and applying 200 - 300 kg of decomposed fermented manure per mu of culture water.

Second, fish species and stocking quality control fish species require symmetrical body, full back tail, intact scales and fins, swimming lively. Fish transportation should try to use fresh water, less organic matter, high dissolved oxygen in rivers and lakes or clean pond water. The transportation mode can be oxygenated by plastic bags and transported by running water vehicles. The breeding species are overwintering species, and are bred when the water temperature rises to 20℃ in the first and middle of May. First, as a matching species, 100~200 fish per mu (specification 50-100 g/tail) are put, and generally grow to 500~1100 g/tail in mid-August. Second, as the main culture of pond, put 1000~2000 fish per mu, the specifications need to be matched with size, can be divided into two to three specifications, at the same time with 200 silver carp, 500 crucian carp, 40 grass carp. Before stocking, fingerlings need to be disinfected with 3-5% saline for about 10 minutes.

III. Water quality control Water quality directly affects the quality and growth of freshwater pomfret culture. If the water quality is fresh and dissolved oxygen is sufficient, it will provide a good water environment for the culture of freshwater pomfret. After the fingerlings are placed in the pond, new water is added every 7 days or so, and the water depth reaches 1.5 meters in the middle of June. After that, new water is frequently added to maintain the water depth of 1.5~2 meters. From July to September, keep turning on the aerator for 1~2 hours at noon every day, sprinkle 1 secondary lime water in the whole pool for 15~20 days, and use 20~ 25kg quicklime per mu.

Fourth, feed feeding quality control feed is mainly artificial feed and chicken intestines and other scraps, protein content of 25%~35%. The fingerlings were trained 3 days after entering the pool and fed regularly. The feeding mode is the combination of concentration and throwing. Feeding should be slow first and then fast, that is, slow feeding to lure fish into the market every time. When the fish enter the market and rise to the surface for feeding, fast feeding and more feeding should be done. When the fish leave in groups with full food, they should be fed less. Each feeding control in half an hour or so, to fish food full and not surplus is appropriate. During production, it is required to seize the best growth period from June to August, appropriately increase the crude protein content of feed, and carefully feed to promote growth. In order to improve the quality of freshwater pomfret, we should feed less chicken intestine and more artificial feed after August. During the feeding period, feeding amount is determined according to the growth rate, water temperature, water quality conditions and feeding status of fish. Feed once a day in the morning and afternoon respectively. Check the feeding situation in the evening of the same day and record the feeding amount every day.

Five, fish disease prevention and control quality control Colossoma brachypomum strong disease resistance, not easy to infect diseases, water temperature above 26ºC, the survival rate is generally above 95%. When the water temperature drops below 20ºC, the juvenile fish are prone to water mildew, small melon worm disease, white skin disease, etc. Fish disease control should follow the principle of "prevention before disease, early treatment when disease exists, prevention more important than treatment". Colossoma brachypomum is sensitive to organophosphorus drugs. When the concentration of trichlorfon reaches 0.2 ppm, Colossoma brachypomum dies. Therefore, trichlorfon is a prohibited drug for Colossoma brachypomum. But to copper sulfate, bleaching powder fish medicine has the bigger tolerance ability, may take the fish disease treatment medicine.