Studies on Bacterial Gill Disease in Salmonids—I

Selection of Bacterium Transmitting Gill Disease

Abstract

A gram-negative filamentous bacterium was isolated from the gills of salmonids, Salmo gairdneri and Oncorhynchus masou, with gill disease. The isolates did not show gliding movement. Growth on Cytophaga agar was pigmented yellow. Colonies were small, translucent, smooth and entire. There was no growth on nutrient agar and meat-extract broth. Acid was produced from glucose and sucrose. Growth was best at 15-20°C.
Attempts succeeded in transmitting bacterial gill disease to fingerling trout by adding pure cultures of the bacterium in aquariums. The experimentlly infected gills showed essentially the same symptoms as seen in naturally occurred gill disease.