Supplements to the description of Zingel streber (Osteichthyes Percidae) with regard to its geographical variability.

On the basis of 232 specimens of Z. streber from different localities, the description of this rare and endangered species is elucidated and its geographical variation studied. Despite the geographical isolation of populations, their morphological differentiation is weakly developed, showing no subspecific character. The population from the Danube River is the most differentiated, showing clear adaptations to severe hydrological conditions. The population of Z. streber from the Nera River in Roumania differs significantly from other populations by the presence of scales in the area between the pelvic fins and shows some relation to the subspecies Z. s.balcanicus described by Karaman from the Vardar River (Aegean Sea watershed).