This study was carried out between May 1999 and June 2000 in order to determine the fish species of the River Mert. In total. 244 individuals from different sampling stations were caught by electric shock, scoop nets, fish nets and fishing lines. In this study, 3 species and 2 subspecies were identified as belonging to 3 families (Cyprinidae, Cobitidae, Gobiidae). The systematic characteristics of fish species were explained. These characteristics were then compared with those in previous studies, and keys to identification were also presented.