Key Points of Ecological Aquaculture Technology for Yellow Catfish in Paddy Fields

I. Selection of the breeding area

The breeding area is 65 hectares, with complete water, electricity and other facilities and convenient transportation.

II. Paddy field engineering construction

1. For the field engineering, 10 mu is taken as one ecological aquaculture unit for yellow catfish in paddy fields. On the inner side of the paddy field ridge, a ring ditch with a top width of 1.5m, bottom width of 0.5m and depth of 0.7m is dug. Within the paddy field, every 40m, a shallow ditch with a top width of 0.5m and depth of 0.2m (cultivated layer) is dug, so that the shallow ditches connect with the ring ditch.

2. For the temporary holding pond, with 10 mu as a unit, one temporary holding pond with a depth of 1m and an area of 60 square meters is built at one end of the paddy field near the water source, for the purpose of cultivating fry and fingerlings.

III. Selection and stocking of fry and fingerlings

1. Selection and transportation of fry and fingerlings Select healthy fry and fingerlings with excellent germplasm, uniform individuals and no public harm. The stocking size is 10g/fish. On May 12, 2004, yellow catfish fry and fingerlings were purchased from Liaoyang City and transported in a live fish transport vehicle equipped with aeration equipment. After arriving at the destination, the fry and fingerlings were disinfected in the water tank on the vehicle with 20g/cubic meter potassium permanganate for 15 minutes, and then the fry and fingerlings were placed into the temporary holding pond.

2. Stocking of fry and fingerlings The "two-stage" stocking method is adopted, namely cultivation in the temporary holding pond and aquaculture in the paddy field. The purchased yellow catfish fry and fingerlings had a size of 6g/fish. Temporary holding and cultivation of yellow catfish fry and fingerlings began on May 12, with a stocking density of 60 fish/cubic meter. On June 27, after the fertilizer application in the paddy field and the residual effects of pesticides had disappeared, the fry and fingerlings in the temporary holding pond were stocked into the paddy field for aquaculture, with a stocking density of 350 fish/mu.

IV. Aquaculture management

1. Domestication Feeding domestication began from the start of temporary holding and cultivation, adopting the domestication method of fixed time, fixed location and unrestricted quantity, with fixed-point feeding 2 times per day (before dusk at 18:00 and at night at 22:00). Before feeding, a signal was first given (making a sound) and then feeding was carried out. After 3 days to 5 days of domestication, more than 80% of the fry and fingerlings could gather at the feed point to eat.

2. Feeding Yellow catfish have different nutritional requirements at different stages of development and growth. We selected special feed with a protein content of 40%, fed 2 times per day, and divided yellow catfish aquaculture feeding into three stages for rational feed combination, so as to meet the nutritional needs of yellow catfish fry and fingerling growth. The first stage was from May to June. The feed composition was entirely special feed with a protein content of 40%, with 2% of the total feed amount of photosynthetic bacteria added each time. After 45 days of temporary holding and cultivation, the fry and fingerlings with a size of 6g/fish reached an average body weight of 50g/fish when leaving the pond, with the heaviest reaching 85g/fish. The second stage was from July to August. The feed combination was mainly prepared from 40% trash fish, 40% soybean meal and 20% bran, supplemented by light-trapped insects, with 3% of the total feed amount of photosynthetic bacteria added each time. The third stage was from September to October, which is exactly the stage of fattening and weight gain for yellow catfish. The feed combination was mainly special feed with a protein content of 40%, supplemented by trash fish, with 4% of the total feed amount of photosynthetic bacteria added each time. Adding photosynthetic bacteria to the feed and appropriately feeding trash fish can improve the quality of yellow catfish. During the aquaculture period, the feed conversion ratio was 1.0.

3. Light trapping of insects At the end of May, as the temperature rose, a large number of insects reproduced and grew. At this time, 1 lighting lamp was installed above the feed platform in the temporary holding pond, and 2 lighting lamps were installed above the feed platform in the paddy field. After the light-trapped insects fell into the water, they could be eaten by yellow catfish, which not only reduced feed costs and increased animal nutrition, but also reduced the occurrence of insect pests in rice planting.

V. Fish disease prevention

1. Persist in changing water and maintain the effective water depth of the paddy field for yellow catfish aquaculture. Before July, the field surface maintained a water depth of 10cm to 15cm; after July, the field surface maintained a water depth of 15cm to 20cm. Change water once every 5 days to 7 days.

2. Regulate water quality. Every 15 days, use 0.2ppm dibromohydantoin to splash the whole field, and every 10 days, use 8ppm to 10ppm photosynthetic bacteria to splash the whole field, keeping the pond water fresh, clean and tender.

3. When the moss has not formed filaments, splash copper sulfate at 1ppm or bleaching powder at 2ppm on the local water surface where moss appears, to thoroughly kill it.

VI. Rice planting and management

The basic principle of ecological aquaculture of yellow catfish in paddy fields is that, compared with monoculture rice, the comprehensive benefits of rice and fish are improved while rice yield decreases slightly.