How to raise yellow catfish well? Disease prevention is key

To successfully farm yellow catfish, the key work lies in doing a good job of pest and disease control for yellow catfish. From fry stocking to adult fish harvesting, careful management is required throughout.

1. Winter preparation must be adequate

1. Clearing the pond and fertilizing the water. Every winter, after the fingerlings are merged into ponds or the adult fish are harvested, drain the pond water, clean out the sludge at the bottom of the pond and repair the pond embankments, and let the pond bake and crack under the sun. This can accelerate soil weathering and achieve the purpose of controlling and eliminating pests and diseases; at the same time, it makes it easier to remove weeds around the pond and reduce the damage to fingerlings by parasites and aquatic insects. Apply 755 kg to 150 kg of quicklime and 1 kg to 1.5 kg of trichlorfon crystals per mu and splash the whole pond for disinfection, thoroughly killing pathogenic organisms. After 5 to 7 days of disinfection, add new water, apply 200 kg of decomposed manure per mu to fertilize the water, and after 7 to 10 days, when large amounts of plankton appear in the pond, the fry can be released.

2. Clearing the pond with bleaching powder. Generally, bleaching powder contains about 30% available chlorine, and its dosage is 15 kg/mu. First dissolve the bleaching powder in water, then splash it over the whole pond. Generally, after 4 to 5 days the effectiveness completely disappears, and fish can then be released.

2. Fingerling stocking depends on the market

Large-sized commercial yellow catfish are welcomed by the market, so large-sized fingerlings of about 30 g each should be stocked for adult fish culture. The stocking amount of fingerlings can be flexibly controlled according to pond conditions, management level, feed supply and fingerling specifications. Generally, about 1,500 yellow catfish fingerlings of 30 g each can be stocked per mu, and about 200 silver carp and bighead carp of 50 g each can be mixed in. The stocked fingerlings should be uniform in size, bright in color, smooth in body surface, free of disease and injury, with intact fins and strong physique. Before entering the pond, they should be soaked in 5% salt water for 10 minutes. Yellow catfish fingerlings are generally stocked in late April each year, and the mixed silver carp and bighead carp should be stocked half a month after the yellow catfish enter the pond, so as to benefit the growth of the yellow catfish.

3. Healthy feeding: grasp the key points

1. Feed formulation. In natural waters, the food of yellow catfish is mainly small shrimp, fish and fish eggs, and some aquatic insects and aquatic plants, so artificial farming can use fresh and live animal feed for rearing.

Use self-made compound feed for domestication feeding. The feed is made by mixing fish meal, meat and bone meal, blood meal, soybean meal, rapeseed meal, dried fish worms, etc. with feed additives. In the early stage, the protein content is above 34% and fat 4%; in the later stage, small trash fish can replace part of the fish meal, with protein content 30% and fat 6%. The feed fed must be fresh, without mold or rancidity.

2. Bait feeding and domestication. Wild yellow catfish prefer to feed at night and hide by day. Under artificial farming conditions, after 5 to 7 days of domestication, they can completely come to the feeding platform to feed during the day. Two days after the fry enter the pond, use artificial feeding for domestication. During domestication, use a fixed feeding signal and conduct fixed-point and fixed-time feeding training. After patient domestication for 5 to 7 days, it is enough; fingerlings domesticated in this way can be fed normally on the second day after entering the pond. Feeding methods can use both manual and mechanical feeding.

3. Feeding amount. The whole feeding process should be divided into three stages. In the first stage, in May and June, feed 4 times daily, with a daily feeding rate of 3% to 5%. In the second stage, in July, August and September, feed 3 times daily, with a feeding rate of 2% to 3%. In the third stage, after October, feed 2 times daily, with a feeding rate of 2%. On this basis, the feeding amount should also be adjusted according to weather and water quality conditions. In the first and third stages, it is recommended to use the satiation method, that is, feeding on the feeding platform. Stop feeding after 90% of the fish leave the platform. In the second stage, because the weather is hot and water quality is prone to fluctuate, it is recommended to feed "90% full", that is, 80% come to the feeding platform, and stop feeding after the fish leave the platform.

In addition, because the yellow catfish has a relatively large mouth opening, the feed particle size should be correspondingly increased. Use 2 mm particle feed as the opening feed, and the adult fish feed particle size can reach more than 5 mm. Sinking hard pellet feed requires the pellets to remain stable in water for 15 minutes; using floating feed will better improve feed utilization.

Before the yellow catfish grows to 3 cm each, it mainly eats aquatic organisms. If aquatic organisms are insufficient, pure dried silkworm pupa powder can be used as a substitute. After 3 cm, it eats artificial compound feed. Two or more fixed feeding platforms can be set up at the corners of the stocking pond and suspended in the water. The number of feeding platforms can be determined according to the size of the fish pond and the number of fish stocked. The feeding platform can be made of simple materials that can sink into the water, and the surface can be covered flat with soft materials such as woven bags. When feeding, add water to the powdered feed or pellet feed and knead it into small balls of 2 to 3 liang in size, throw them onto the platform, and let the fish come onto the platform to eat by themselves. Feed once each morning and evening, and each feeding amount should basically be eaten up.

4. Water quality management is also key

In adult yellow catfish farming, water quality management is the most critical, and a clear water environment needs to be maintained. To prevent water aging, inject 30 cm of new water each month in May and June, and change 15 cm of water every half month from June to September, keeping the water depth at 1.2 m to 1.5 m. Persist from June to September in using 15 ppm quicklime to splash the whole pond once a month, to purify and disinfect the water quality and reduce excessive organic suspended matter. Every half month, use 5 kg of quicklime (or 2 kg of bleaching powder) for local treatment once at the feeding ground and the aerator. Persist in observing the water body's algal phase and algal concentration, and according to water color use inorganic fertilizers (urea, superphosphate, potassium dihydrogen phosphate, etc.) to regulate water fertility, keeping transparency at 30 cm to 35 cm; according to dissolved oxygen measurements and weather and water quality conditions, scientifically use the aerator. On sunny days, persist in running the machine for 1 hour in the early morning and afternoon. In rainy, stuffy and hot weather, make full use of mechanical aeration to supplement the insufficient dissolved oxygen in the water body. Dissolved oxygen should be kept above 3 mg/L.

5. Drug selection depends on efficacy

Yellow catfish has strong disease resistance, and generally there are no major diseases in farming. However, yellow catfish is a scaleless fish, and its tolerance to commonly used drugs is not as good as that of the four major Chinese carps. During rearing, due to the influence of season, temperature, water quality, feeding, the scaleless characteristics of the fish body surface, and bacteria and parasites in the fish pond, local infections and parasitic diseases can also be caused. This requires attention to observation in ordinary farming and early prevention against abnormal conditions. When preventing and treating diseases, try to use high-efficiency, low-toxicity drugs, and determine the drug varieties to use by observing efficacy.

1. Insecticides. Splash the whole pond with 0.03 ppm concentration of decis per cubic water body, or splash with copper sulfate and ferrous sulfate at a concentration ratio of 0.15:0.05 ppm. The above insecticides are relatively good against (dactylogyrus, trichodina) and other parasites, but the two drugs can only be used alone, cannot be mixed or used alternately, and must not be used in excessive amounts.

2. Antibacterial and anti-inflammatory agents. For oral drugs (pressed into pellets and mixed evenly in feed), mix 10 g of furazolidone with 20 g of oxytetracycline, add to 50 kg of bait, and feed continuously for 3 days, twice daily. Oral penicillin capsules can also be used, added to the feed (5 g) and fed continuously for 3 days, twice daily. For disinfecting the fish body, use 0.25% bleaching powder solution or penicillin powder diluted and concentrated for soaking for 10 minutes. The above oral medicated feed is best prepared and fed immediately. Prepare once and feed for three days, and never leave it for a long time. It mainly targets fish with bacterial infections.

3. Treatment of hemorrhagic disease. Use 50 kg of raw salt per mu and splash the whole pond. To treat yellow catfish diseases, refuse to use trichlorfon drugs to kill insects, otherwise it will bring adverse consequences.

During stocking and transportation, try to avoid injuring the fish body, to prevent infection with water mold in the low-temperature seasons of early spring, autumn and winter. In high-temperature seasons, if hemorrhagic edema disease occurs, use chlorine dioxide to splash the whole pond twice continuously, which can effectively treat it.