Techniques for the Four Key Periods of Yellow Catfish Farming

Carrying out yellow catfish farming in lakes, reservoirs, ponds, rivers and other water bodies can effectively utilize the water body and obtain relatively high economic benefits, and is an effective way for the vast number of farmers to adjust their planting and breeding structure and increase income. However, because the yellow catfish has omnivorous feeding habits, broodstock cultivation is quite difficult, and it is a scaleless fish with different requirements for feed and farming management at different growth stages. To achieve high yield and high efficiency in farming, one must master the farming techniques for four key periods.

I. Broodstock cultivation period

1. Broodstock collection As broodstock, fish are required to have bright body color, a plump body shape, a strong physique, and to be free of disease and injury, aged over 2 winters, with male individuals above 14.8cm and female individuals above 11.7cm, and a male-to-female ratio of 1:1.50. When selecting male and female broodstock, pay attention to reasonable identification. The best time to collect broodstock is in the winter of the previous year.

2. Broodstock cultivation The collected broodstock can be soaked and disinfected in 2%-3% saline water for 10 minutes to 15 minutes, then placed in a dedicated pond for cultivation. The pond area should be more than 2 mu, the water depth should preferably be about 1.5m, the pond bottom is required to be flat, the water quality should have a certain degree of fertility, and the pond water transparency should be about 30cm. Plants such as Potamogeton crispus and Hydrilla verticillata can be planted in the pond to provide food organisms and habitat for the broodstock; some freshwater shrimp can also be stocked as a polyculture to fully utilize the water body and provide food organisms for the yellow catfish. During the broodstock cultivation period, small fish, small shrimp, or crushed snails and clams can be fed, and eel feed can also be fed, paired with animal-based bait such as snails and clams. During the broodstock cultivation process, flush the water once every 2 days to 3 days to promote gonadal development of the broodstock.

II. Fry cultivation period

After 20 days to 30 days of cultivation in the breeding pond, yellow catfish fry can reach the summer-fingerling size of 2cm to 3cm in body length. During the fry cultivation period, the pond area is required to be 1 mu to 2 mu, the water depth about 1m, pH 7 to 8, dissolved oxygen above 5mg/L, and the pond water is required to undergo strict disinfection. The best palatable food organisms for newly stocked fry are rotifers, nauplii, or small cladocerans, so before the fry are stocked, manure fertilizer should be spread over the whole pond at 150kg/mu to 300kg/mu to fertilize the water. When the fry reach 0.9cm to 1.0cm in body length, a small amount of compound feed can be fed, 2 times per day, with the daily feeding amount accounting for 3% to 5% of the total fish body weight, but fertilization must be carried out in a timely manner so that the fry always have abundant and palatable food organisms.

III. Fingerling cultivation period

Fingerling cultivation is the process of cultivating summer fingerlings about 2cm in body length to large-size fingerlings of 5cm to 6cm in body length. The cultivation pond is required to have an area of more than 2 mu, sufficient water source, and good water quality, with a stocking density of 10 fish/sq m to 15 fish/sq m. During the cultivation process: first, scientific feeding is required. Because yellow catfish have the habit of feeding in groups, feed trays should be set up properly in the pond, and feed should be placed on the feed trays, fed 2 to 3 times per day, with the daily feeding amount at about 5% of the total fish body weight, and the crude protein content in the feed above 40%; second, regulate the water in a timely manner, regularly add and change water, fertilize reasonably, ensure fresh water quality, sufficient dissolved oxygen, and abundant food organisms, and when necessary, turn on aerators to increase oxygen; third, disinfect regularly, using quicklime or bleaching powder to disinfect the feed trays once every half month, and antibiotics and other drugs can also be added to the feed to ensure the survival rate of fingerlings.

1. Pond-based main culture

(1) Pond selection Select scattered small ponds with an area of 2 mu to 5 mu, requiring sufficient water source and water quality meeting aquaculture water standards. The pond should have convenient water intake and drainage, a flat bottom, and be able to ensure a water depth of 1.5m to 2.0m. At the same time, the pond bottom soil is best if sandy, with bottom sludge controlled at about 10cm, and good water retention and fertilizer retention. Finally, each pond must be equipped with mechanical equipment such as aerators and water pumps.

(2) Disinfection and fertilization Before fry and fingerlings are stocked, both new and old ponds must be cleaned and disinfected. Old ponds should have excess sludge removed, retaining only 10cm, and 150kg/mu quicklime should be used for dry pond clearing to thoroughly kill parasites, pathogens, and wild miscellaneous fish. After drying for 1 week, store water to a depth of 80cm. A 30-mesh sieve cloth should be installed at the water inlet for filtration to prevent wild miscellaneous fish and fish eggs from entering. Apply fermented organic manure to fertilize the water at 150kg/mu to 200kg/mu, and stock fingerlings after large numbers of zooplankton appear in the pond water.

(3) Fingerling stocking Large-size commercial fish are welcomed by the market, so large-size fingerlings of about 30g each should be stocked for grow-out rearing. The stocking amount of fingerlings can be flexibly controlled according to pond conditions, management level, feed supply, and fingerling size. Generally, for yellow catfish fingerlings of 30g each, the stocking density is about 1500 fish/mu, and about 200 fish/mu of silver carp and bighead carp of 50g each can be stocked as a polyculture. The stocked fingerlings are required to be uniform in size, bright in color, smooth in body surface, free of disease and injury, with intact fins, and strong in physique. Before entering the pond, they need to be soaked in 5% saline water for 10 minutes. Yellow catfish fingerlings are generally stocked in late April each year, and the polycultured silver carp and bighead carp fingerlings should be stocked half a month after the yellow catfish enter the pond, to benefit the growth of the yellow catfish.

(4) Feed feeding In natural waters, the food of yellow catfish is mainly small fish and shrimp, fish eggs, and some aquatic insects and aquatic plants. In artificial farming, fresh live animal bait can be used, such as small fish and shrimp, livestock and poultry processing scraps, etc., and soybean cake, peanut cake, bran, etc. can also be fed. Generally, compound feed is mostly used for domestication feeding. The feed is made from imported fish meal, meat and bone meal, blood meal, soybean meal, rapeseed meal, dried fish worms, etc., combined with feed additives. In the early stage of farming, the protein content is above 35% to 45%, and the crude fat content is 5% to 8%; in the later stage of farming, small miscellaneous fish can replace part of the imported fish meal, and a protein content of 30% and a fat content of about 6% are sufficient. The reference formula is: fish meal 25%, soybean cake 20%, rapeseed cake 30%, @#@245@#@ meal 20%, corn meal 3%, minerals 2%, vitamins 0.2%.

(5) Regulating water quality To prevent water aging, inject water once each month in May and June, each time replacing 30cm of new water - from June to September, change water once every half month, each time changing about 15cm, maintaining the water depth at 1.2m to 1.5m. At the same time, adhere to regular disinfection, using 15ppm quicklime to spread over the whole pond once a month, to purify and disinfect the water quality. Scientifically use aerators according to dissolved oxygen measurements and weather and water quality conditions, keeping dissolved oxygen above 3mg/L.

(6) Disease prevention and control Yellow catfish have relatively strong disease resistance. As long as water quality is controlled strictly according to requirements and routine disinfection and prevention are done well, diseases rarely occur. Once disease occurs, it should be diagnosed promptly and accurately, and medication should be used precisely for treatment. Because yellow catfish are scaleless fish, their tolerance to commonly used drugs is inferior to that of domesticated fish, so prevention should be the priority, and highly effective, low-toxicity drugs should be used as much as possible during treatment. It is recommended to use regular feeding of medicated bait as a preventive measure, using oxytetracycline and Chinese herbal medicines such as rhubarb and Isatis root at an inclusion rate of 0.1% to 0.4% for 3 days to 5 days each month. During capture, stocking, and transport, try to avoid injuring the fish body, to prevent infection with water mold in the low-temperature seasons of early spring, autumn, and winter.

2. Pond polyculture When dedicated yellow catfish feed is unavailable and there is no sufficient supply of bait organisms such as small miscellaneous fish and shrimp, yellow catfish winter fingerlings can be polycultured in ponds mainly culturing other fish species, with a stocking density of 80 fish/mu to 150 fish/mu. After 5 months to 6 months of farming, winter fingerlings of about 15g each can grow to 100g each, with a per-mu yield of about 10kg of commercial yellow catfish.

3. Cage culture

(1) Farming conditions First, carefully make the cages. The cages are made of polyethylene. The mesh size of the netting is generally required to be 2.0cm to 3.0cm, the mesh size of the net bottom is 1.5cm, the cage specifications are preferably 12 sq m to 24 sq m, the cage shape is square or rectangular, and the cage depth is 2.0m; second, place the cages reasonably. The water quality of the water area where the cages are set is required to be lively and refreshing, with relatively high dissolved oxygen. Place the cages in the water 1 week before fingerling stocking, so that algae adhere to the cage walls and reduce fish body abrasions. The spacing between cages should be 2m to 3m. In areas with strong sunlight, a shade cover should be added above the cages; third, pay attention to water source and water quality. A sufficient, stable, and pollution-free water source is required. The water depth at the cage setting site is required to be above 2.5m, and good water quality should be maintained, requiring water transparency above 30cm and not a large water exchange volume.

(2) Fingerling stocking First, the source of fingerlings must be production from regular hatcheries, with uniform size, bright body color, no injuries on the body surface, strong physique, lively swimming, and excellent purity. Artificially bred fingerlings are best; second, the stocking time for cage-cultured yellow catfish is generally around the Spring Festival, when fingerlings begin to be stocked. Before the fingerlings are put into the cages, the fish body needs to be soaked in 5% saline water; third, the stocking density is generally 100 fish/sq m to 150 fish/sq m. In addition, some blunt snout bream and fine-scaled xenocypris can be appropriately polycultured to fully utilize bait organisms and purify the cage water quality.

(3) Feed feeding First, the feed fed must be fresh, free of mildew, and free of rancidity. It is best to choose complete feed produced by regular manufacturers, and the feed is best in powder form. When feeding, mix the feed into a paste and place it on the feed tray in the cage; second, do a good job of domestication feeding. Start artificial domestication feeding 2 days after the fry and fingerlings enter the cage, and after patient domestication for 5 days to 7 days, normal feeding can begin; third, feed reasonably, feeding 2 times to 3 times per day, with the feeding amount at 3% to 5% of the total fish body weight.

(4) Daily management First, standardize operations, regularly check fish growth, carefully observe and analyze fish conditions, handle problems promptly when found, keep cage culture logs, and record daily water temperature, feeding, feeding amount, dead fish, and disease-related conditions, so as to accumulate experience; second, frequently scrub away dirt and attached algae on the cages so that the water body can fully exchange; third, frequently inspect the cages and repair any damage promptly, so as to avoid fish escape or entry of ferocious fish; fourth, as reservoir water levels rise and fall, adjust the cages promptly to a suitable water depth position; fifth, according to market conditions and fish growth, carry out timely partial harvesting and restocking to maximize the best economic benefits. Cage-cultured yellow catfish generally begin to be harvested in batches from early August @#@136@#@.