Study of Biological Characteristics of Paracobitis hircanica (Mousavi-Sabet et al., 2015) in Zav River, Golestan National Park

To study the biological characteristics of Paracobitis hircanica with 150 fish samples that obtained in December 2015 to May 2016 with trawl net.  Sex ratio of male to female was 1:0.65 that showed significant difference between sex ration of male to female in population (X2 = 6.83, p < 0.05).  Maximum total length and weight were 87 mm and 5.30 g for females, 104 mm 7.31 g for males. The weight - length relation of female was W = 0.0085 TL2.89 (r2 = 0.97) and the weight - length relation of male was W = 0.0109 TL2.74 (r2 = 0.98) and the total relation was W = 0.0099 TL2.80 (r2 = 0.97). The results showed Isometric growth for female and negative allometric growth for male and population (t-test, tmale= 6.31, tfemale = 1.61, tpopulation= 5.03, p < 0.05). Average absolute fecundity were 328.86, while the relative fecundity (eggs/g) were 110.56. Eggs diameters were ranged from 0.45 to 1.79 mm with a mean value of 0.99 mm. The highest mean Gonadosomatic (GSI) for females in April and for males in May was observed, 8.06 and 1.43 for female and male respectively.