We have been contacted by a number of anglers in relation to several Deveron salmon showing signs of a white fungus (photo below). We believe the fungus to be Saprolegnia, a fungal-like organism that infects freshwater fish. Infections often appear as grey, brown or white fur-like growths on the skin, fins and gills. The fungus often infects damaged skin and open wounds, and is therefore usually considered as a secondary infection.
Saprolegnia is a natural infection of salmon and trout, therefore it is not unusual to see occasional infections in wild fish, especially as we approach their natural spawning time. Incidence of the disease tends to be highest when larger numbers of salmon are present in a small area, particularly if they are prevented from moving upstream and the fish become stressed. Congregations of fish in low water are particularly susceptible.