Morphological characteristics and variation of gudgeon, Gobio gobio (Actinopterygii: Cyprinidae), from the Odra River drainage, Poland

Background. The gudgeon is a small fish of limited economic importance. Species of the genus Gobio bear a strong superficial resemblance to one each other, what has led to the misidentification of Central European gudgeons for many years. Consequently, accurate information about Polish populations of gudgeon is still scarce and more studies are needed to fill this gap. The purpose of the presently reported study is to describe the gudgeon on the basis of its morphological characters and to compare the results published by other authors. Materials and methods. A total of 46 specimens of the gudgeon, Gobio gobio, were caught in the Zimnik Stream, the SkĂłra system, the Odra River drainage, western Poland, in October 2002. For each fish, 24 biometric features of the body and 20 features of the skull were measured. Selected meristic features (external and internal) were determined. Cephalic sensory canals were studied and their pores were counted. Results. The coefficient of variation for the body proportions of the sample of gudgeon from the Odra River drainage ranges from 1.7% to 7.2% and its principal features are as follows: D III 7–9; A III 6–7; P I 11–15; V I 6–8; l.l. 37–41. Two rows of pharyngeal teeth are present, most frequently, in 2.5–5.2 pattern. The total number of vertebrae ranges from 46 to 48 (mean 47.38). Conclusion. This study shows that the sample analyzed has the shortest head length in relation to other measurements and the body length, as compared to other populations from Polish rivers. The majority of values of meristic features do not differ significantly from those found in literature. The presently provided internal meristic and osteological features of gudgeon are among very few such data available.