Technical key points for polyculturing silver and bighead carp in snakehead farming
I. Pond clearing, preparation and disinfection
The pond area for polyculturing silver and bighead carp with snakehead is preferably 6-8 mu. If the area is too small, water quality tends to deteriorate easily, and during the main summer period, high-temperature seasons easily trigger disease. If the area is too large, production input is high, and management is inconvenient. The pond water depth should be about 2 m, with no or little bottom mud left. Weeds around the pond must be cleared, and the pond embankments must be tamped and reinforced to prevent seepage and leakage. 20 days before stocking fingerlings, use quicklime to thoroughly clear the pond at 100-150 kg per mu. After 10 days, use bleaching powder (effective chlorine content 30%) to clear the pond once more at 5-7 kg per mu. After one week, water can be added and fingerlings stocked.
II. Fingerling stocking
1. Snakehead fingerlings The suitable stocking time for snakehead fingerlings is early October. After entering the pond, the fingerlings can feed and recover their condition, and the overwintering survival rate is increased. Fingerlings of the following year can also be stocked in March-April. Before entering the pond, they must be strictly disinfected for prevention. Generally, soak in 3%-5% salt water for 10-15 minutes before stocking. The stocking size is best with locally produced fingerlings to avoid injury to the fish body caused by long-distance transport, which affects the survival rate, and also to avoid introducing pathogenic bacteria from other places.
2. Silver and bighead carp fingerlings and other fingerlings Silver and bighead carp fingerlings can be stocked around the Spring Festival, preferably before the Spring Festival. Generally, for ponds mainly culturing snakehead, 200-250 silver and bighead carp per mu are added, along with 60-80 carp and crucian carp. The size of silver and bighead carp is 6-8 fish/kg, and the size of carp and crucian carp is 10-15 fish/kg. Before entering the pond, the fingerlings must also be strictly disinfected before stocking.
III. Feeding management
1. Feeding Adhere to the “four fixed” principles. Depending on the pond area, 1-2 feeding sites can be set up to concentrate the snakehead around the feeding sites, which can create a scrambling-for-food situation, increase feed intake, and reduce feed waste. The feed type is mainly freshwater small trash fish, supplemented by marine small trash fish. During the peak feeding season, the feeding amount of bait fish is 6%-8% of fish weight. Before feeding, wash the small trash fish. For frozen marine small trash fish, after thawing, soak in 3%-5% salt water for 20 minutes for disinfection. Feeding gradually is effective. Once most fish are full and swim away, feeding can stop. Silver and bighead carp, carp and crucian carp no longer need feeding.
2. Pond patrol Mainly observe fish feeding, activity, disease trends, and environmental changes twice a day in the morning and evening. Regularly remove residual bait, remove excess aquatic plants from the pond, prevent fish escape, and start the aerator in time if there are signs of floating head.
3. Water quality management In high-temperature seasons, snakehead has a large feed intake and a large metabolic rate, and water quality very easily turns black and smelly, causing water body deterioration, which is not conducive to the growth and development of snakehead. Therefore, in high-temperature seasons, generally do a small water change every 3 days and a large water change every 7 days. Where conditions permit, micro-flowing water aquaculture can be used, and the aquaculture water level should be maintained at about 2 m. At other times, change water according to water quality changes. Generally, change 1/3 of the water every week, and do a large water change every 10-15 days. In stuffy and hot weather, special attention should be paid to timely water changes or adding fresh water.