The hypothesis of environmentally related life history variations between two Rutilus rutilus caspicus populations was investigated by comparing Gomishan and Anzali populations along the southern shores of the Caspian Sea. The roach growth rate in the Anzali wetland was higher than in the Gomishan wetland. There were significant differences in growth patterns between males and females from both wetlands, however the sex ratios were not significantly different. Fecundity or reproductive investment (Gonadosomatic index – GSI) of the Gomishan roach was significantly more than the Anzali roach. In both areas the absolute fecundity was significantly positive correlated to age and total length.