Pollution-free management key points for raising yellow catfish (Pelteobagrus fulvidraco) as a supplementary species in lotus ponds

Lotus ponds contain many benthic organisms, aquatic insects, plankton, and pond weeds, which can provide food for the fish, while the fish feces and leftover bait can provide fertilizer for the lotus, and the fish activity loosens the soil, providing good soil conditions for lotus growth. Because lotus leaves shade and block light, the light intensity in the lotus pond environment is relatively weak, which suits the yellow catfish's requirement for feeding and growth under low light.

Pond construction. Choose a pond with abundant water sources, good water quality, fertile soil, flat terrain, convenient water intake and drainage, and strong water and fertilizer retention. The pond depth is 1-1.5 m, the mud thickness at the pond bottom is 30-40 cm, and the pond area is 667×3-667×5 sq m, with an east-west orientation being preferable.

Lotus planting. 15-20 days before planting the lotus; apply 800-1000 kg of fermented organic fertilizer such as chicken manure per 667 sq m, spread the fertilizer evenly, plow and rake the pond bottom level, then use 80-100 kg of quicklime for routine disinfection; plant the lotus seedstock in spring on March 20-25, using 100-150 kg of seedstock per 667 sq m. After the lotus is planted, store water to a depth of 10 cm, and filter the water inlet with a 30-mesh silk sieve to prevent wild fish and fish eggs from entering.

Fry and fingerling stocking. After the lotus grows its first lotus leaf, stocking can begin. 5-7 days before stocking the fry and fingerlings, apply 150-200 kg of fermented pig and cattle manure and 15-20 kg of superphosphate per 667 sq m to fertilize the water quality, and at the same time add 20 cm of fresh water so that the water level reaches 30 cm. To increase the market size of the commercial fish, stock 300 high-quality large-size yellow catfish fingerlings per 667 sq m, with an average individual weight of about 30 g. Before the fingerlings enter the pond, soak them in 3% salt water for 5-10 minutes to disinfect and prevent disease. The stocking time is April 15-20. After 20 days, when the lotus has grown five leaves, add another 10 cm of fresh water, and at the same time stock 10 grass carp and 20 silver carp per 667 sq m, with a size of about 20 g per fish, as companion cultured fish. Afterward, gradually raise the water level.

Feeding management. 1. Feeding and baiting. Because domesticated fingerlings are stocked, there is no need for bait training. Start feeding on the 3rd day after the fingerlings enter the pond, feeding twice a day, at 7-8 a.m. and 4-5 p.m. respectively, with a daily feeding rate of about 3%. The specific feeding amount should be flexibly controlled according to the weather, water quality, and the fish's feeding and activity conditions. The bait is a self-made compound feed, mainly composed of soybean meal, wheat bran, corn, blood meal, fish meal, feed additives, etc., with a crude protein content of 30%. The bait is floating, with a particle size of 2-5 mm. The feed is fed at a fixed point on the feeding platform. In addition, to save artificial feed and increase live bait for the fish, after entering July, install two insect-attracting lamps above the pond, one incandescent lamp hung 20 cm above the lotus leaves, and one black light lamp hung below the lotus leaves, 10 cm above the water surface, with the two lamps on the same vertical plane. After dark, first turn on the upper white light lamp. When a large number of moths are found, turn on the lower black light lamp and turn off the upper white light lamp. After half an hour, turn off the lower lamp, then turn on the upper lamp again, and repeat this operation. The moth-attracting effect is quite good.

2. Water quality regulation and disease prevention. As the temperature continues to rise, add fresh water in time. By early June, the water level rises to its highest, reaching about 0.5-0.8 m. From July to September, change 10 cm of water every 15 days, and once a month splash the whole pond with 15 mg/L quicklime water to regulate water quality and disinfect and prevent disease. Because yellow catfish is a scaleless fish, except for quicklime, other external-use drugs should not be used. Disease prevention mainly uses oral drugs, feeding medicated bait containing 0.2% oxytetracycline or chloramphenicol for 3 days every half month. The fish live in a specific ecological environment, and in addition to the ecological symbiotic mutual benefit between fish and lotus, disease rarely occurs during the culture period.

Harvesting the product. Before harvesting the lotus, the fish should be caught successively for market, and all should be caught by early October, so as to lower the water level, raise the ground temperature, and promote the lotus rhizomes to grow larger and plumper. When the terminal leaf of the lotus appears, it indicates that the lotus is mature. When most of the standing leaves of the lotus are still green, the lotus rhizome is tender, crisp, and sweet, and the market price at this time is high. When the leaves turn yellow and withered and the old rhizomes are dug, drain the pond water, dig them out with a shovel, and they can be sold on the market.