Reproduction of Capoeta damascina (Valenciennes, 1842), a cyprinid fish, in Zayandeh-Roud River, Iran

Reproductive characteristics of siahmahi, Capoeta damascina (Valenciennes, 1842), a native cyprinid in the Zayandeh-Roud River, were investigated by monthly sampling from March 2007 to April 2008. Among 689 specimens captured, the overall sex ratio was 1 : 1.57 (males : females). Males matured at age 2(+). Females matured between ages 4 and 6, with 100% maturity at age 7(+). Based on the gonadosomatic index (GSI), the reproductive period peaked between May and June. Histological and macroscopic characteristics of the gonad indicated the species to be group-synchronous. Absolute fecundity varied greatly with female size, ranging 2520 to 72 650 (mean 24 800 +/- 17 800) eggs for females 25.5-54.2 cm TL and weighing 320-2340 g. Fecundity increased with fish age, averages being 9446 +/- 8028 for 4(+) old females and 54 503 +/- 13 803 eggs in mature 8(+) year old females.