All provided sections showed the fungal organism only in cross section. The fungus lacks internal structures such as spores, daughter spherules, cleavages, septa, vacuoles, buds and hyphae. With diligent search, rare trypanosomes may be found within blood vessels. No specific gross or histologic lesion of visceral organs could be attributed to this protozoan. Ichthyophonus hoferi is the most common marine fungal pathogen of fish.
Infected fish swim abnormally, are lethargic, and listless.
The scaled skin may become granular and roughened over affected areas. Some fish develop a dark coloration on the lateral line which may progress to discoloration of the entire fish. Histologically, fungal spores are bounded by a granulomatous inflammatory reaction. Greenmead Drive, College Park, MD 20740. Green DE, J Andrews, and JM Abell.