The relationship between length and weight and some biological characteristics of Tinca tinca (Linnaeus, 1758) in the Anzali Wetland was investigated. A total of 102 specimens of T. tinca were collected on monthly sampling intervals from spring to winter 2019. The mean total length of fish was 15.97±1.51, minimum 13 and maximum 22.5 cm. The fork length was 15.58±1.55, minimum 12.7 and maximum 22.3 cm. Mean fish weight was 62.64±21.15 g with minimum 30 and maximum 174 g. The obesity factor index was 1.49±0.18 in the whole population and 1.41±0.11 in males and 1.55±0.20 in females with minimum values in autumn and maximum in spring. Mean hepatic index was 1.05±0.76 for the whole population, 1.29±0.89 in males and 0.90±0.63 in females with minimum values in spring and maximum in autumn. The mean gonadosomatic index was 5.62±4.58 for the whole population and 3.35±2.1 in males and 7.02±5.12 in females with the minimum in winter and maximum in spring. The relationship between total length and weight for all fish was W=0.025 L2.8123, female W=0.0363 L2.6907 and male, W=0.0066 L3 .2724. According to the b value of the length-to-weight relationship, T. tinca in the Anzali Wetland has an isometric growth pattern indicating similar growth and length growth rate. In the present study, the obtained CF>1 was obtained indicating a proper feeding conditions of the species in the Anzali Wetland.