Biometric indices of Clarias gariepinus and Oreochromis niloticus in selected Gongola river corridors in Gombe State, Nigeria

Abstract

The length-weight relationship and organosomatic indices, are useful metric for detecting chronic stress in fish within aquatic ecosystems. The biometric indices of Clarias gariepinus and Oreochromis niloticus collected from the Gongola river corridors in Gombe State were investigated. Fish weight, standard and total length, the weight of the liver, spleen and gonads were all measured and record. Moreover, Fulton condition index, Hepatosomatic index (HSI), splenosomatic index (SSI) and gonadosomatic index (GSI) were calculated using standard
methods. All the mean concentrations obtained in the reference dam had condition factor <1 and this may be attributed to the over exploitation of the large size fish species of C.gariepinus and O. niloticus because of the high clarity of the water. Most fish samples collected from Gwani were found to be in good healthy stage. The highest HSI mean value was 0.98±0.82% indicating that these specimens from all the study areas were all < 1 because the study species were under stress due to high amount of rainfall in wet season. 2.47±4.04% was the highest GSI mean concentration of O. niloticus found in dry season at Gwani sampling locations showing elevation in body weight. This study also recorded low SSI mean values of 0.05±0.03% (0.05%) and 0.07±0.12% (0.07%) in O. niloticus and C. gariepinus at Balanga (the reference) dam and the variations in the morphology of spleen between species may be responsible for the low values of SSI. There were slight changes the biometric condition which may result from the stress conditions, suggesting a more comprehensive health assessment index in future research of the sampling sites.