Determination of heavy metals and proximate analysis of Merluccius spp and Clarias gariepinus

Abstract

This study investigated the heavy metal concentrations and proximate composition in stockfish and catfish samples from the Choba market near the University of Port-Harcourt, Rivers State. The research aimed to provide comprehensive data on the safety and nutritional value of these commonly consumed fish species. Five samples of each fish species were analyzed for heavy metals using Atomic Absorption Spectrophotometry and proximate composition following standard analytical procedures. The results revealed that stockfish contained higher protein levels (61.38%) and ash content (15.10%) compared to catfish (46.88% and 11.80%, respectively). However, catfish exhibited substantially higher fat content (13.81%) than stockfish (3.5%). While both species showed similar carbohydrate levels (approximately 15%). Heavy metal analysis demonstrated that stockfish generally contained higher concentrations of most analyzed metals. Iron showed the highest concentration in both species, with stockfish containing 4.102 ppm compared to catfish’s 2.231 ppm. Lead content was notably higher in stockfish (0.315 ppm) than in catfish (0.132 ppm). Arsenic and nickel levels were also slightly higher in stockfish, while manganese showed higher concentration in catfish. The findings suggest that while both fish species offer distinct nutritional benefits, the elevated heavy metal concentrations, particularly in stockfish, warrant careful consideration. The study recommends regularly monitoring heavy metal concentrations, especially lead, and advises consumers to vary their fish consumption patterns.