Bacterial gill disease of freshwater fishes.

Bacterial gill disease (BGD) was found in fry and fingerling brook trout at first. Mortalities were influenced by the temperature of water. Detailed studies show that more than one type of bacterium may be involved with BGD. Pathologic changes in gills are caused by other diseases also. Results of various studies done on BGD are shown. The signs and pathology, the diagnosis, the source and reservoir of infection, the mode of transportation, the environment and bacterial gill disease, the incubation and communicability, the susceptibility and resistance, and the geographic range of bacterial gill disease are given. Control of bacterial gill disease is broken down into three parts: immunity, sanitation, and therapy. Treatment with certain chemicals is usually effective in treating bacterial gill disease, in accordance with an improvement of environmental conditions.