The purpose of this study was to clarify difference between two species of the genus Zacco, Z. platypus and Z. temmincki, and differences among geographical populations of the same species of the genus Zacco, by means of protein electrophoresis, The obtained present results were compare with one another, and their relative similarities were determined. The percentage similarity between Z. platypus and Z. temmincki was 67%. This result proved that these two species can be genetically distinguished since this similarity valus is low enough to treat as two independant species, Meanwhile, average percentage similarity among seven populations of Z. platypus was 0. 89%, and that of Z. temmincki was 0. 91%. This data revealed that interspecies variation of Z. platypus is higher than that of Z. temmincki, By the present results, it is elucidated that the muscle protein patterns between two species of genus Zacco are species-specific, then these two species can be distingushed each other, whereas there was not mearly genetic differences among geographical populations of the same species since their protein patterns were appeared very similary.