Comparative Analysis of Metal Levels in Clarias gariepinus and Water from River Benue and Commercial Fish Ponds in Makurdi

Abstract

Aims: The present study assessed toxic metals content in the water, feeds and fish organs (liver, gills, and kidney) of Clarias gariepinus from River Benue and selected fish ponds within Makurdi metropolis of Benue State. Place and Duration of Study: Sample: A total of eighteen (18) Clarias gariepinus fish samples were purchased within Makurdi metropolitan area of Benue State, Nigeria. Methodology: Toxic heavy metals in fish samples were digested using standard procedures and determined using HG-AAS. Results: The mean concentration (mg/kg) of heavy metals in fish organs from fish ponds and River Benue are respectively as follows –As: 0.90 and 0.77; Hg: 0.91 and 1.75; Pb: 1.42 and 1.67. The mean concentration (mg/kg) of As, Hg and Pb in feeds were (0.13, ND, and 0.13 respectively), water (mg/L) 0.10, 0.30 and 1.57, respectively. Hg and Pb had higher concentrations in river Benue compared to the fish ponds. However, As was higher in the fish ponds compared to river Benue. With the exception of As that falls within the EU set limit of fish, Hg and Pb are above the WHO and EU set limits of fish. Conclusion: It is thus evident that adequate environmental policies are necessary to reduce the risk of heavy metal contamination of fish in Makurdi.