Title: Study of reproductive characteristics of Capoeta trutta in Gamasyab River, Kermanshah Province, Iran
Abstract: The reproductive characteristics of Capoeta trutta were monthly reviewed in the Gamasyab River Kermanshah province for one year from August of 2008 till July of 2009. Totally, 252 fishes were caught, of which 167 pieces were male and 85 were female. The sex ratio in this study was obtained as 1.96 ♂: 1 ♀. The maximum total length of the male and female fishes in Gamasyab River was measured as 205.25 and 303.5 mm respectively. Four reproductive characteristics including absolute fecundity, relative fecundity, Gonad somatic index (GSI) and ova diameter were measured and recorded from the fishes of Gamasyab River. The mean absolute fecundity of fishes in this river was 7756±736, whose minimum and maximum was obtained as 1920 and 17505 respectively. The mean relative fecundity of fishes in this river was calculated as 50.65±3.61. The average of Gonad somatic Index (GSI) of male and female fishes was achieved as 5.182.42 and 3.441.11 respectively, which showed a significant difference in the level of 5 percent (P<0.05). The mean ova diameter of fishes in Gamasyab River was measured as 0.9±0.09 mm, for which the range of 0.12-1.90 was obtained. Considering the fact that the Gonad somatic index of this fishes is maximized in May, the time for spawning was determined to be in May and for reproduction to be from March till June. Epithelial nodules appeared in March, maximize in May and disappear in June. The average water temperature and the amount of