An investigation of the bactericidal action and fish toxicity of two homologous series of quaternary ammonium compounds

Bacterial gill disease when uncontrolled causes heavy losses among hatchery fish. The disease is characterized by a proliferation of the gill epithelium overlaid with masses of myxobacteria. The characteristic hyperplasia probably causes death by preventing the proper interchange of gases between the water and the blood stream of the fish.

A number of strains of myxobacteria differing primarily in pigment formation have been isolated from diseased fish. These cultures formed neither microcysts nor fruiting bodies when grown on the conventional media used for culturing myxobacteria, and may therefore be considered to be members of the genus Cytophaga. Although organisms of this type are characteristically found on diseased gill tissue, it has not been possible to infect healthy fish with the organisms isolated. There is, therefore, reason to question that these organisms are the etiological agents of the disease. On the other hand, it seems likely that these organisms contribute to the manifestations of the disease, because on successful treatment the bacteria disappear first; this is followed by a disappearance of the hyperplasia.