Studies on the aspects of biology of Barbus occidentalis (Cyprinidae) of River Uke, Nasarawa State, Nigeria were conducted during wet and dry seasons. La Motta Tracer (model 1766) was used to determine the physicochemical parameters. A total of 219 specimens were obtained from fisher folks on landing site. The fisher folk used fishing gears such as cast nets, traps from March-August 2017. The specimens were used to determine morphometric parameters (length, weight, depth and eye diameter), fecundity, gonadosomatic index. The study showed the range values of the physicochemical parameters obtained were D.O 2.5 - 5.1mg/L, Temperature 27.0 - 32.1oC, pH 6.8 - 8.0, salinity 20 - 70ppm, TDS 70 - 110ppm, EC 20 - 161μS respectively. The weight of Barbus occidentalis sampled ranged from 15.0 - 996.9g. The biggest male weighed 996.9g while the biggest female weighed 620g. Fecundity ranges from 1257 - 6576 for the period under review, the relationship between fecundity and other parameters were highly significant (0.928) indicating positive correlation between biological parameters and fecundity. The physicochemical parameters obtained during the dry season were higher than those of the wet season; there is a correlation between some physicochemical parameter of River Uke and biological parameters of the specimen. The result of this study has revealed that the fish have high reproductive potentials. Hence adequate regulation is required as to enhance sustainability of this important fish of River Uke.
Key words: Physico-chemical, Fecundity, Gonadosomatic index, Barbus occidentalis, River Uke