An abscess in the nasal region of a cod fish, held for experimental work, resulted in a large swelling. Purulent exudate filled the nostrils. Among the signs of distress was an apparent lack of equilibrium. Histological examination of the nasal area showed extensive destruction of the muscle and connective tissue and leucocytic infiltration.

Six microorganisms were isolated from the infected region. The suspected pathogen was identified as Vibrio anguillarum. The other isolates, felt to be secondary invaders or bacteria normally present in sea water, were Achromobacter, Flavobacterium and Pseudomonas species. The vibrio grew well at salinities of 2–5% and at temperatures of 10–24 C. It exhibited strong proteolytic activity.

Intramuscular injection of the suspected pathogen into mummichogs (Fundulus heteroclitus) resulted in a lesion similar to that originally observed.

The results of electron microscopy are described.