Coldwater DiseaseA disease of young salmonid fishes caused by a myxobacterium Cytophaga psychrophila. Coldwater disease occurs when water temperatures fall between 45o to 50o F. This disease is characterized by lesions in the caudal peduncle or on the isthmus or other areas of the body. The caudal fin is often completely destroyed and the fish may become dark colored.
An effective treatment for coldwater disease is medicated feed containing oxytetracycline (Terramycin) at a rate of 50 mg/kg/day for 10 to 14 days. Where possible, raising the water temperature above 50o F will cause the infestation to subside.