Some reproductive Features of Cobitis sp. from Dough River in the southern Caspian Sea basin

Cobitis sp. is an endemic spined loach species from the Dough River in the southern Caspian Sea basin, (Golestan Province, Iran). To provide some reproductive features of this fish, sampling was performed at monthly intervals throughout the year and 417 individuals were collected. The specimens ranged in total length from 27.1 to 92.9 mm and total weight from 0.11 to 6.79 g. The spawning of spined loach of Dough River occurs from March to June. The highest mean value of gonadosomatic index (GSI) observed in April as 1.96 for males and 6.61 for females. Egg diameter ranged from 0.3 to 1.3 mm, with a mean value of 0.9 mm. Absolute fecundity varied from 155.04 to 3212 eggs. Fecundity relative to total weight fluctuated from 55.41 to 634.76 eggs g^–1. This species is among those spawning early in spring compared to other species of this genus from southern Caspian basin.