Abstract
We studied food habits of exotic largemouth bass and fish community in twelve farm ponds in Isawa Ward, Oshu city. The main prey of bass with rich fish community was fish, whereas bass with poor fish fauna preyed mainly insects and zooplanktons. Population number of native fish, Pseudorasbora parva, in ponds with bass was significantly less than those in ponds without bass. Furthermore, the size distributions of Japanese crucian carp, loach and freshwater common goby in ponds with bass were different from those in ponds without bass. It seemed the impact of bass predation influenced to not only population number but also body size of native fishes such as cyprinids and benthic fishes seriously.
