Prevention and Treatment of Oral and Lower Jaw Boils in Freshwater Pomfret Farming

[Cause] The pathogen may be bacteria, but it has not been isolated and identified. The main conditions for the pathogen to cause this disease are the oxidative deterioration of meat residue and oil paste in pelleted feed after long-term storage, and the deterioration of water quality.

[Symptoms] Diseased fish show reduced feed intake. They swim slowly at the water surface and respond sluggishly, sometimes developing spasms. Dead diseased fish have boils in the oral cavity and on the lower jaw, and the sites of the boils are consistent. Some boils are red, swollen and raised; some boil surfaces are ulcerated; and on some, along the lower edge of the lower jaw and the mouth margin, there are also mung bean-sized boils. Some diseased fish have a distended abdomen, with the abdominal scales stretched apart, feeling like a file to the touch, and a large amount of ascites is found when opened.

[Epidemic and Harm] This disease is currently mainly seen in large-sized fish, generally occurring from July to August, with a disease course of about 10 days, an incidence rate exceeding 30 percent, and high mortality. Polycultured silver carp and grass carp do not develop the disease.

[Diagnosis] Diagnosis can be made by examining the boils in the oral cavity and the ascites of the diseased fish.

[Prevention] 1. Maintain good water quality. 2. Do not feed oxidatively deteriorated bait.

[Treatment] 1. Replace part of the pond water, and splash bleaching powder over the whole pond at 1 mg/L. 2. Soak and wash the diseased fish with 8 mg/L oxytetracycline solution for 15 minutes. 4. When necessary, inject penicillin at 50,000 to 90,000 units per kg of body weight, which is effective.