Distribution of the Siberian sculpin (Cottus poecilopus) was studied based on data collected from 138 sites in the Poprad River catchment area (the Vistula basin, southern Poland). The population density was found to range from 3 to 203 inds·100 m^-2. Large differences in fish density were found between the streams and between sites within a stream. The Siberian sculpin were significantly more abundant at shallow sites: densities of up to 50 inds·100 m^-2 were recorded at sites of mean depth <15 cm. In low gradient stream sections (<25 m·km^-1) with numerous pools (>50% bed surface area), the density exceeded 50 inds·100 m^-2. The species density was statistically significantly, negatively correlated with the distance from the stream origin (r = -0.7453), stream bed gradient (r = -0.8652), and mean depth (r = -0.7078). On the other hand, a significant negative correlation was found between the pools sections and the density (r = -0.7496). The relationships between the density and the environmental factors analysed are presented in the form of multiple regression.

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