Affected aquarium fish show several symptoms such as anorexia, ‘popeye’, skin discolouration and external lesions such as ulcers, nodules and ‘fin rot’. Cold water salmonids may show no external signs of disease other than mortality, but post-mortem examination may reveal greyish-white lesions in the kidney, liver and spleen.
There is some debate as to whether infected fish can be successfully treated for these bacterial diseases. The destruction of infected stock and comprehensive disinfection of premises is usually recommended