Abstract
Recent molecular research indicates that several distinct species have been confused under the name Gobio gobio (L.); thus, comparative investigations of numerous local populations are urgently needed. The present study presents and discusses detailed morphometric characteristics of 82 individuals from the G. gobio complex of nine tributaries of the upper Vistula River (southeast Poland) within the context of the known variability of this species. The specimens analyzed generally resemble G. gobio s. stricto in a number of morphometric and meristic characters. The results are rather consistent with previous literature data on Polish populations of the "common gudgeon"; however, as long as molecular analyses are not available, precise identification is impossible.