LESIONS IN THE MUSCULATURE OF CAPTIVE AMERICAN PLAICE HIPPOGLOSSOIDES-PLATESSOIDES CAUSED BY THE FUNGUS HORMOCONIS-RESINAE (DEUTEROMYCETES)

Round black lesions were found on the ventral side of 8 juvenile Ameri can plaice Hippoglossoides platessoides housed in the aquarium at the Department of Fisheries and Oceans Research Laboratory, Halifax, Nova Scotia, Canada. The wild plaice caught on Sable Island Bank, Nova Scot ia, were held in 800 and 3200 l tanks supplied with a continuous flow of fresh prefiltered seawater at ambient temperature. The lesions numb ered 1 or 2 per fish, varied from 5 to 20 mm in diameter and usually h ad a large central crater. Light microscopy and SEM revealed that the ulcers were surrounded by a rim of hyperplastic epidermis and containe d numerous branched, septate fungal hyphae and Gram-negative bacteria, host erythrocytes, macrophages, and cellular debris. Fungal hyphae an d necrosis extended through the dermis and musculature to the vertebra l column. While the epidermis was intact over smaller lesions, hyphae could be seen on the surface of the skin, and extending along the scal es through the epidermis and into the dermis. The fungus was identifie d as Hormoconis (Cladosporium) resinae (Deuteromycetes), a species tha t is not only ubiquitous in terrestrial, freshwater and marine environ ments, but often occurs in petroleum products. This is the first recor d of the fungus as a pathogen in a marine organism.