Epidermal lesions and fungal infection on the perch, Perca fluviatilis L., in Windermere

An account is given of the histological changes associated with epidermal lesions on the Windermere perch, Perca fluviatilis L., between the months of January and March, 1976. During the later stages of the development of the lesions an apparent succession of fungal colonization was observed. A total of five genera of fungi were identified with Leptomitus lacteus appearing early in the infection and Achlya tending to dominate the more advanced lesions. The initial cause of the lesions has not been identified but the possibility of Argulus damage is discussed.