Pathology of ulcerative mycosis in Atlantic menhaden Brevoortia tyrannus

Abstract

The pathology of ulcerative mycosis in naturally affected Atlantic menhaden Brevoortia tyrannus is described. Ulcerative mycosis is a deep granulomatous dermatopathy caused by infection with oomycete fungi. The response to this fungal infection was similar to that described for other granulomatous diseases. The posteroventral portion of the body was most frequently affected, with 67% of all lesions observed in this area. Lesions prepared to begin as small, focal infections on or near the skin surface which rapidly enlarged and often extended into adjacent viscera. In many fish, this necrotic mass of tissue was sloughed, leaving a crater-shaped ulcer. Only fish with small ulcers had any evidence of healing, suggesting that this disease may cause high mortalities in affected populations