Ecological observations on the Fungal Colonization of Fish by Saprolegniaceae in Windemere

Abstract
(1) The colonization of clean (apparently uninfected), dead salmonid fish by Saprolegniaceae was studied both in the laboratory and in Windermere. Colonization proceeds in two stages in water: initially there is superficial mycelium, which is easily removed, and later there is a deeper penetration into the epidermis and dermis. There was evidence that colonization can occur as an intimately mixed mosaic of different Saprolegniaceae. (2) Live char and other salmonids are normally colonized only by the specific Saprolegnia pathogen in Windermere. However, this specificity broke down when there was colonization of dead tissue on a live char. This situation was seen to be analogous to that in ''perch disease''; it is deduced that the role of the various fungi here is saprophytic only. (3) In post-mortem, salmonid fish killed by the specific Saprolegnia pathogen do not attract other Saprolegniaceae subsequently and explanations for this are proposed.