Detailed Explanation of Key Points for High-Yield Pond Culture Techniques of Longnose Catfish

The longnose catfish, also known as the Jiangtuan, is a valuable economic fish species in China. After several years of high-yield pond culture, our yields have basically reached 400-500 kg per mu. The culture techniques are summarized as follows.
I. Pond conditions. The water quality is required to be fresh with relatively high dissolved oxygen and a pH of 7-8.2. Therefore, the pond should be located close to a water source, with convenient drainage and irrigation, and in a quiet environment. The pond area should generally be 1000-3000 sq m, with a water depth of 1.5-2 m, rectangular in shape, oriented east-west, with walls hardened with brick, stone, or cement, and bottom sludge not exceeding 10 cm. Each pond should be equipped with one 3 kW paddlewheel aerator.
II. Fingerling stocking. Select artificially domesticated and cultivated one-winter-age fingerlings that are robust in constitution and uniform in size. Generally, stock 800-1200 fingerlings of 70-100 g per mu, together with 250-300 silver carp of 150-200 g, 75-100 bighead carp, and additionally 5 mandarin fish or perch to control wild miscellaneous fish in the pond. Do not stock competing fish species such as common carp, grass carp, or tilapia. Fingerling stocking is best done in early March. Ten days before stocking, apply quicklime at 100-150 kg per mu as a slurry broadcast over the entire pond; after 7 days, fill with water to the required level. Before stocking, dip the fish bodies in a 15-20 mg/L potassium permanganate solution or 3%-5% salt water for 15 minutes to kill pathogens and harmful organisms.
III. Feed feeding. After the fry and fingerling stage of diet conversion training, the longnose catfish mainly feeds on compound feed, with a crude protein content of 40%-45%. The main ingredients are imported fishmeal, dried fish, soybean cake, peanut cake, wheat bran, yeast powder, mineral salts, vitamins, etc., made into hard pellet feed with particle sizes of 3 mm, 4 mm, and 5 mm. At the initial stage, the feed particle size is 3 mm; as the fish gain weight, it is changed to 4 mm and 5 mm. Feeding should be done at a fixed location, fixed time, and fixed quantity, with a feeding platform built on one side of the pond. After stocking, training is carried out: first, train with sound at the feeding platform to condition the pond fish, then slowly feed by hand scattering. Feed twice daily at 8 AM and 8 PM, with the morning-to-afternoon feeding ratio of 4:6. Each operation should be done carefully until the fish school is satiated and leaves. The daily feeding amount is generally 1.5%-3%.
IV. Water quality regulation. The longnose catfish prefers fresh water with relatively high dissolved oxygen. Normally, water quality management should be strengthened, insisting on frequent addition of fresh water, timely operation of aerators, and rational use of biological agents to regulate water quality. June to September is the peak growth season for the longnose catfish, so water should be flushed every other day, and sludge discharged and water changed once a month, with the water exchange volume being 1/4 of the pond water. Increase aeration equipment as much as possible and operate aerators at appropriate times: turn on at noon on sunny days, at dawn on cloudy days, at midnight during continuous rainy days; do not turn on in the evening, turn on early when fish gasp at the surface, and turn on every day during peak growth season. Operating duration: short at noon, long at midnight; short in cool weather, long in muggy weather; long when load is high, short when load is low. Periodically apply photosynthetic bacteria at 10-20 g per cubic meter. Periodically broadcast quicklime water, generally once every half month during the culture period, at 5-10 kg per mu. Always maintain pond water dissolved oxygen at no less than 5 mg/L, pH of 7.2-8.2, and water transparency of 30-40 cm, but adjust flexibly according to season and pond water fertility. The water should not be too lean; medium fertility leaning toward light is best. If water source is abundant and temperature is suitable, micro-flow water supplemented by timed flushing can also be used.
V. Daily management. Patrol the pond frequently, insisting on patrolling every morning, noon, and afternoon, removing residual feed and debris and cleaning the feeding platform, observing whether pond fish show gasping at the surface. In extreme heat season or sudden weather changes, increase nighttime patrol frequency or arrange night shift management. Start feeding early: begin feeding training on the second day after stocking. In conjunction with pond patrols, observe the weather, water color, and fish feeding conditions daily. Every 15 days, randomly sample fish to check feeding and fatness conditions, and by weighing and counting, estimate the growth rate of the fish, the total pond fish biomass, and the feed efficiency, to determine the next stage's feeding amount.
VI. Disease prevention and control. Every half month, broadcast quicklime over the entire pond at about 10 kg per mu. Long-term add 1.5% allicin to the feed. Each month, use Yusukang to make medicated bait and feed for 3 consecutive days to prevent enteritis. Each month, alternately broadcast Chlorsanwang and copper sulfate over the entire pond, with a concentration of Chlorsanwang at 0.2-0.3 g per cubic meter and copper sulfate at 0.3-0.5 g per cubic meter. During feeding management, always observe the feeding conditions of the fish school. If abnormal reactions or diseased fish are found, treat with the appropriate medication as early as possible.