This study involves the investigation of Tinca tinca (L., 1758) living in Kapulukaya Reservoir in Turkey. It was observed that the fish reach sexual maturity at the age of III and the breeding period starts in May and ends in July. The mean monthly gonadosomatic indices varied from 1.38 +/- 0.06 (in October) to 8.01 +/- 1.03 (in May). According to monthly variations of the GSI, spawning of the tench takes place between May (8.01 +/- 1.03) and June (5.50 +/- 0.57). The average egg number per fish was estimated to be 23403 +/- 17047. The eggs diameters varied from 0.50 mm to 1.33 mm (mean 0.86 mm). The relations between the fecundity (F) and body length (L) and body weight (W) were found as F = 0.037799 x L (1.0212) (r = 0.70) and F = 0. 00000175 x W (2.8696) (r = 0.62).