Diet Composition and Selectivity in O+ Perch (Perca fluviatilis L.) and its Competition with Adult Fish and Carp (Cyprinus carpio L.) Stock in Pond Culture

Food composition and selectivity of 0+ perch (Perca fluviatilis) were studied under the experimental pond conditions during the growing season in 2000. The diet of perch fry consisted mainly of chironomid larvae and pupae and zooplankton, mainly cladocerans (Bosmina longirostris, Chydorus sp., Ceriodaphnia sp., Alona sp.) and copepods. Both chironomids and cladocerans were consumed with positive selectivity. The food items of lesser importance were water beetles (genera Rhantus, Hydrobius and Hydroporus), water bugs Corixa affinis and mayfly larvae Caenis sp. Chironomid larvae were most important food items also in the diet of both adult perch and 2+ carp. Also 0+ perch contributed considerably to the diet of adult perch and benthic food resources (bryozoans and organic debris) including supplied feed cereals were of biggest importance for common carp. The perch competes with parental fish and common carp for approximately one third of available food items, whilst adult perch and carp compete for a half of them