Comparative Estimation of the Stamina of the Perch Perca fluviatilis (Percidae) and the Roach Rutilus rutilus (Cyprinidae)

Abstract In an experimental assessment of the stamina of fish the perch was shown to be almost twice as strong as the roach in terms of swimming power. In the early stages, interspecific differences are weakly expressed, but, with an increase in body size and weight, differentiation increases significantly. The rapid growth rate of burst swimming speed of the perch provides the ability to feed on more mobile objects. With age, the diet of fish is diverged to a large extent, roach feeding mainly on sedentary animals and plant food compared to perch almost completely switching to feeding on fish and benthic invertebrates. This allows for the potential competitive tensions in the cohabiting species to be reduced.