Sublethal effects of three ectoparasites on fish

Vulnerability to predation, resistance to high temperature, weight‐length relationships, and fecundity were compared for fish with and without or with light and heavy infestations of three ectoparasites. The fish and parasites were fathead minnow ( Pimephales promelas ) with anchor worm ( Lernaea cyprinaceae); brook trout ( Salvelinus fontinalis ) with gill lice ( Salmincola edwardsii); and yellow perch ( Perca flavescens ) with black‐spot ( Neascus of Crassiphiala bulboglossa). The only sublethal effect found was that of gill lice, which reduced resistance of brook trout to high temperature. None of the three ectoparasites increased vulnerability offish to predation by piscivorous fish.