SUMMARY.In laboratory experiments, prey selection of zooplankters by starved perch fry (Perca fluviatilis) from Windermere, English Lake District, is temporally variable and there is usually, in the short‐term, a persistent succession from one actively selected prey species to another. Provided that the prey is visible, the patterns of prey selection are maintained irrespective of the accessibility of the prey. The fish do not optimize their energy intake per effort. The method of observing predation activity by fish shows qualitative and quantitative prey selection as time progresses in great detai