My research activities are conducted to evaluate and develop appropriate sampling and censusing techniques for fishes, conduct behavioural studies and identify the ecological requirements of fishes in a variety of aquatic habitats. My principal interest is in the reproduction and recruitment of European fishes in lowland rivers. Research is directed to understand and predict the effects of the environment and biotic interactions, such as competition, predation and parasitism, on reproduction and recruitment in fishes. Most of my current research activity involves investigations of environmental stress to fish assemblages, and the ecology of expanding gobiid fishes in Central Europe. The results of many studies have wide implications for fisheries and wildlife management and conservation.