Life history traits of the flying barb Esomus danricus (Hamilton,1822) (Cyprinidae) in the Ganges River,northwestern Bangladesh

The present study describe the first life-history traits of threatened fish esomus danricus from the ganges river,northwestern bangladesh. this study also calculates the form factor,size at first sexual maturity and natural mortality of e. danricus from world-wide different water bodies using available literature. sampling was done,using traditional fishing gears including cast net,square lift net and conical trap during january to december 2014. a total of 309 individuals ranging from 2.94-6.10 cm total length and 0.25-1.38 g body weight were analyzed in this study. the length frequency distributions showed that the 4.00-4.99 cm total length size group was numerically dominant and constituted 50.00% of the total population. the allometric coefficient (b) of the length-weight relationship indicates negative allometric growth (b < 3.0) for e. danricus in the ganges river. the results also indicate that the length-length relationships were highly correlated (r2 ≥ 0.974). the allometric condition factor varied from 0.015 to 0.018 and fulton's condition factor varied from 0.607-0.985. also the relative condition factor ranges from 0.923 to 1.127 and minimum and maximum values of relative weight were 92.185-112.727 in the ganges river. the fulton's condition factor is the best index for assessing the wellbeing of e. danricus in the ganges river. according to wilcoxon signed test the relative weight did not show any significant difference from 100 (p = 0.295),indicating the balance habitat for e. danricus. the form factor was calculated as 0.0033 and the size at first sexual maturity for combined sexes of e. danricus was estimated as 3.98 (∼ 4.00) cm total length in the ganges river,northwestern bangladesh. in addition,the mean natural mortality was estimated as 2.31 year-1. these results will be useful for sustainable conservation of this threatened fish in the ganges river and surrounding ecosystem. copyright 2016 zoological society of pakistan.