The population structure, mortality and growth of the tench [Tinca tinca (L., 1758)] in Civril Lake was investigated, using 506 fish caught with various gill nets between February 1998 and January 1999. The percentages of females and males in the population were 38.34% and 61.66%, respectively, and the overall female-male sex ratio was 1:1.61. Specimens ranged from 11.4 to 28.8 cm in fork length, and from 27.7 to 420.4 g in weight. The age distribution was IN in the population. For all individuals, the length-weight relation and von Bertalanffy growth parameters were W = 0.018 L-3.01, and L-infinity = 33.85 cm, W-infinity = 723.18 g, k = 0.284 year(-1) and t(0) = -0.895 year, respectively. The rates of total mortality, natural mortality and fishing mortality were 60.46%, 30.19% and 30.27%, respectively.