Four populations (two from rivers and two from lakes) of roach Rutilus rutilus (L.) were tested for a variation of morphological features depending on the given habitat. 23 biometric and 11 meristic variables were analysed. The compared fish populations showed little variability as regards the meristic features. Lake roaches were characterised by higher values of biometric characteristics than the river populations. The habitat affected the selected biometric variables. The following features: eye diameter, length of the caudal peduncle and head depth were the least changeable. The greatest differences between the fish populations were identified in the case of head and body width. River roaches had higher fins and a greater predorsal length. The lake roach populations were showed greater pectoral – pelvic fin distances. Moreover, the fish from lakes were characterized by lower variability of countable traits as compared with the river fish.