Detailed Explanation of Key Techniques for Monoculture of Yellow Catfish in Ponds

1. Pond preparation

The fish pond is rectangular, oriented east-west, with an area of 1.5 mu and a water depth of 1.5-1.8 m. It has convenient drainage and irrigation, and is equipped with one 1.5 kW floating spray aerator. The pond bottom is flat with little silt, which facilitates harvesting. Ten days before the fry are stocked, 100 kg of quicklime per mu is mixed with water and splashed for disinfection. Three days later, 200 kg of fermented pig manure per mu is applied, and pond water is added to a depth of 1 m. The water inlet is filtered with 60-mesh silk gauze. One day before stocking, a summer-fry net is used to make one empty haul.

2. Fry stocking

1) Fry preparation

The fry are taken from the farm's artificially bred Jiang yellow catfish (also known as Bagrid catfish). When the fry are reared with water fleas to 1 cm, they are fed live tubifex. In 3-5 days they can reach 2 cm. At this time they are switched to fish slurry, and pelleted feed is soaked and mixed with a little soft-shelled turtle feed to make a paste for feeding. After 15-20 days of feeding, the fish grow to 5 cm and can be stocked in the pond.

2) Fry stocking

Stock 4,000 fish per mu, totaling 6,000 fish. Before stocking, soak them in salt water for 3-5 minutes. Ten days later, stock 300 silver carp fry weighing 75-100 g each and 100 bighead carp fry weighing 100 g each.

3. Feeding management

1) Feed feeding

At the eastern end of the fish pond, set up a 2 sq m feeding platform along the pond edge, 30-40 cm from the pond bottom. Feed with fish slurry and soaked feed for 3 days to attract the fish to gather on the feeding platform to eat. Then stop feeding fish slurry and switch to crushed feed. The daily feeding amount is 3%-5% of fish body weight, at 9-10 a.m. and 3-5 p.m. each time. In the morning, feed 1/3 of the whole day's amount, and in the afternoon feed 2/3. When feeding, follow the "four fixed and four look" principle, that is, flexibly judge by looking at the weather, water quality, water temperature, and the fish's feeding situation, and keep production records.

2) Water quality regulation

Seven days after the fry are stocked, add pond water to a depth of 1.5 m in 3 applications. About every 30 days, splash 8 kg of quicklime per mu once. About every 30 days, add 10-15 cm of new water, alternating with the limewater splashing, and start the aerator in a timely manner to keep the water quality "fresh, lively, and clean."

3) Fish disease prevention and control

In addition to splashing quicklime, from June to October use disinfectant powder in hanging bags around the feeding platform, 250 g each time, replacing once every 7-10 days. Haul the net once a month to check fish growth so as to adjust the feeding amount, and at the same time remove wild trash fish. Use a summer-fry net when hauling, and try to avoid injuring the fish spines when closing the net. After removing trash fish, transfer them into fry cages, sample, count, and weigh them. To prevent infection caused by puncture wounds from the hard spines of the same species, soak the harvested fish in salt water for 3-5 minutes, which works very well. Do not use sensitive drugs such as trichlorfon or miechongling.

4. Harvest

Yellow catfish were stocked on June 4, and pond drying and harvesting began on December 11. A total of 217 kg of yellow catfish were obtained, with individual weights of 45-80 g, mostly around 65 g. A total of 564 kg of feed was used, and the feed conversion ratio was 2.6.

5. Experience and discussion

Raising yellow catfish has high benefits and great production potential. With proper fish disease prevention and control, no disease occurred in the fish pond throughout the year. Strengthening feed training can change the yellow catfish's habit of feeding at night, facilitate production management, and improve feed utilization. However, the following aspects should be noted in aquaculture:

1) Density should not be too high

At the end of July, the weather continued to be muggy and hot. On the night of July 26, the yellow catfish pond suffered severe oxygen deficiency and pond turnover. Despite desperate rescue efforts, more than 2,000 fish still died, which was the main reason affecting yield. Therefore, stocking density should be reduced, and about 3,000 fish per mu is appropriate.

2) Feed composition

The complete feed used had a protein content of 33% and a crude fat content of 4%. The nutrient composition was somewhat lacking, which affected the individual growth of yellow catfish. It is recommended to use complete feed with a protein content above 36%, or supplement with animal-based feeds such as fish slurry and minced snail and mussel meat, and strive to raise them to market size within the same year, shorten the production cycle, and improve production efficiency.