بررسي ريخت سنجي، سن و رشد سياه ماهي Capoeta capoeta gracilis در نهر زرين گل، استان گلستان، ايران

An Investigation on morphology, age and growth of Capoeta capoeta gracilis in Zarrin-Gol stream, Golestan Province of Iran

We investigated the morphology, age and growth of Capoeta capoeta gracilis in Zarrin-Gol Stream of the Golestan Province of Iran during October 2007. One hundred specimens of Capoeta capoeta gracilis were sampled for which the length range was measured to be between 39.9-149.8 mm. The 0+ year age group was the most frequent (59%) and the 3+-4+ age groups were the least frequent classes (1%). The longest specimen was 149.8 mm in total length. Fish in age group 0+ had significantly larger inter orbital eye length in comparison with the fish in age groups 1+ and 2+ (P0.05). Fish in age group 2+ had significantly smaller head length and head height than the fish in age groups 0+ and 1+. Instantaneous growth of the fish at the age 3+ was very much lower the than the younger age groups. We determined a negative allometric power length-weight relationship for the species as W=0.00003 xL2 822 (r2=0.91). The Von-Bertalanffy equation coefficients were determined at Lt = 223.8(1 - exp[- 0.185(f +1.8)].