P>The study investigated the age, growth and sex ratio of Tinca tinca L., 1758 in Seyhan Dam Lake, Turkey and determined its first population structure data in the lake. Fishermen had introduced tinca into the lake between 2001 and 2002. A total of 1284 T. tinca (778 males and 506 females) were captured between January and December 2007 by gill nets of various mesh sizes. The sex ratio was 1 : 1.53 females to males. Total lengths and weights ranged from 12 to 29 cm and 27 to 403.3 g. Ages in both sexes ranged from 1 to 5 years. For all individuals the length-weight relation and von Bertalanffy growth parameters were W = 0.063 x L2.51 (r = 0.981), and L-infinity = 50.86 cm, k = 0.112 year-1, t(o) = -1.551 year.