Visceral necrosis of goldfish, Carassius auratus (L.): a new bacterial disease

. Recent shipments of goldfish into Canada have suffered major mortality within a short time of arrival. The pathology and bacteriology of several of these diseased fish are described. Lesions were either acute and necrotizing with haemorrhage, or they were granulomatous. In either case, the spleen was a prime target, although in severely affected animals other organs were similarly involved; these included anterior and posterior kidney (plus endocrine elements), liver, intestine, mesentery and brain. Associated with these lesions were intracellular bacteria, which were often arranged in a Chinese letters-like configuration, and which are presumed to be the cause of the disease. The Gram-negative bacterium was isolated from all fish, but its characteristics were such that it was not easily classified and its taxonomy therefore remains uncertain.