Prevention and Treatment of Common Diseases in Yellow Catfish Farming

Hemorrhagic edema disease

Hemorrhagic edema disease in yellow catfish is caused by bacterial infection. This disease is most harmful during fry or adult fish farming, and is especially prevalent during fry rearing, with a mortality rate as high as 80%. In hot seasons, the disease breaks out suddenly, strikes fiercely, and spreads quickly.

Symptoms  The body surface of diseased fish turns yellowish, with increased mucus; the skin of the pharynx breaks down and becomes congested, forming round holes; the abdomen swells, the anus becomes red and swollen and protrudes; the head becomes congested, the dorsal fin swells, the bases of the pectoral and pelvic fins become congested, the fin rays rot, and in severe cases the abdomen splits longitudinally from the pectoral fins to the pelvic fins, with bile leaking out. A large amount of bloody fluid or yellow gelatinous material accumulates in the abdominal cavity, there is no food in the stomach or intestines, the stomach is pale, the intestines are filled with yellow liquid, the liver is clay-yellow, the spleen is necrotic, and there are dark mold-like spots on the kidneys.

Prevention and treatment  Maintain good water quality, keeping the dissolved oxygen content of the pond water above 5 mg/L; appropriately reduce the stocking density of fry. After the disease occurs, disinfect the water body once a day for 3 consecutive days. At the same time, add 0.6-0.7 g of tetracycline per kg of feed to make medicated bait and feed it once a day for 3 consecutive days; when feeding minced fish meat, 1% table salt must be added to the feed.

Enteritis disease

Enteritis disease in yellow catfish is caused by infection with Aeromonas punctata. It mainly harms fingerlings and adult fish. The peak prevalence mostly occurs when the water temperature is 25-30°C.

Symptoms  The abdomen of diseased fish swells, the anus is red and swollen, and when the abdomen is gently pressed, yellow mucus flows from the anus. In mildly affected fish, the esophagus and foregut become congested and inflamed; in severe cases, the entire intestine becomes inflamed and pale red, with blood and pus filling the intestinal tract. Diseased fish swim alone away from the group, move slowly, and have reduced appetite.

Prevention and treatment  Thoroughly clear and disinfect the pond; do not feed moldy or spoiled feed, disinfect live feed with a 2%-3% table salt solution, and regularly add 1% table salt or 0.1% fresh garlic juice to the feed; splash 0.5 g of dibromohydantoin dissolved in water per cubic meter of water over the whole pond; add 0.4-0.5 g of oxytetracycline powder per kg of feed and feed continuously for 5-7 days.

Trichodinasis

Trichodinasis in yellow catfish is caused by Trichodina parasitism. It mainly harms yellow catfish fry and fingerlings.

Symptoms  Diseased fish are restless and anxious; in severe infections, diseased fish swim wildly along the pond edge, showing a “horse-racing” phenomenon; microscopic examination shows large numbers of Trichodina parasitizing the fish's gill filaments and skin mucus.

Prevention and treatment  Splash 0.7 g of copper sulfate and ferrous sulfate mixture (5:2) dissolved in water per cubic meter of water over the whole pond, or use 30 kg of chinaberry leaves per mu of water surface, boil them, and splash the decoction over the whole pond.

Ichthyophthiriasis

Ichthyophthiriasis in yellow catfish is caused by Ichthyophthirius multifiliis parasitism. When fish are overcrowded, feed is insufficient, and the fish body is weak, fish are susceptible to Ichthyophthirius multifiliis infection.

Symptoms  Small white spots are visible to the naked eye on the body surface of diseased fish, and in severe cases the body surface appears to be covered with a white film; microscopic examination of gill filaments and skin mucus shows large numbers of Ichthyophthirius multifiliis.

Prevention and treatment  Soak the fish body in a 50-60 mg/L formalin solution for 10-15 minutes; disinfect the diseased fish pond with formalin; splash 2 g of methylene blue dissolved in water per cubic meter of water over the whole pond once a day for several consecutive days.

Anchor worm disease

Anchor worm disease in yellow catfish is caused by Lernaea parasitism. April to June is the prevalent season.

Symptoms  In the early stage of the disease, diseased fish show restlessness, slow swimming, and emaciation. The parasitic sites become congested, inflamed, swollen, and develop red spots. Lernaea parasitism can be seen with the naked eye.

Prevention and treatment  Splash 0.3-0.4 g of 90% crystalline trichlorfon dissolved in water per cubic meter of water over the whole pond.