ICHTHYOFAUNA DIVERSITY OF OKWII AND IKWO RIVERS ISHIAGU, EBONYI STATE, NIGERIA

Okwii River which is of economic importance to the inhabitants of Ishaigu is suspected to be disturbed by mining wastes from an active mining pit with deposits of lead and zinc. However, there is a dearth of information on the ichthyofauna of Okwii River which could serve as indicators of water quality. Fish samples were caught biweekly using gillnets from 3 different stations for 3 months and identified using standard guides. Data were analysed using descriptive statistics and Shannon-Wiener’s species diversity (H'). A total of 194 fish samples belonging to four families and six species were collected. The four (4) families identified were: Clariidae, Cichlidae, Hepsetidae and Clarotidae amongst which Cichlidae exhibited the highest relative abundance (71.65%), contrasting with Clarotidae's lowest (3.09%). Amongst the species identified, Oreochromis niloticus (38.66%) and Pelmatolapia mariae (31.44%) were the most abundant while Clarias gariepinus (3.61%), Chrysichthys nigrodigitatus (3.09%), and Coptodon zilli (1.55%) were the least abundant. Station 2 (Downstream Okwii River) showed the highest diversity (H'=1.145), while Station 3 (Ikwo River) had the lowest (H'=0.685). The research findings show a wide contrast in species composition in comparison with other studies in the surrounding water bodies, an expression of the ecological stress in Okwii River. The low fish diversity and abundance suggests that the capacity of the river to support a healthy fish population has been considerably diminished. Therefore, there is an urgent need for regular pollution control measures, and natural habitat restoration works to conserve the biodiversity of the river