Abstract We studied the probability of occurrence, distribution and abundance of eight small fish species in 512 small rivers at the eastern edge of Europe in a region of high geographical and environmental heterogeneity. Stone loach, common minnow, and gudgeon were recorded in more than 50% of the study sites. Common minnow was the most abundant species, contributing 66% of all captures. Elevation, depth, and width of the river were the main environmental factors influencing the distribution of more than half of the studied fish species. Our research in the eastern edge of Europe shows that fish preferences in terms of probability of occurrence, abundance, and niche breadth for environmental factors can vary greatly, even among closely related species. depth.