Disseminated hexamitiasis in Siamese fighting fish.

One hundred forty Siamese fighting fish became inappetent and lethargic and developed swollen abdomens. One hundred fish died, many with perforated stomachs. Hexamitid parasites were found in large numbers in the abdominal cavity and in the mesentery and the parenchyma of the liver, spleen, and kidney, where they were closely associated with a chronic inflammatory response. Species of bacteria recovered from the peritoneal cavity were believed to be secondary invaders. The 40 surviving fish, including some sick ones, were treated with nifurpirinol at the rate of 0.2 mg/L and 5 mg/kg of body weight, by means of a bath and a feed medication, respectively. The sick fish recovered, and no more died.