Assessment of Heavy Metals (Ni, V, Se, Cu) in Fish Species Channa obscura and Lates niloticus in Alaro Stream in Ibadan, Nigeria

A study was conducted to evaluate the concentration of heavy metals, specifically nickel (Ni), vanadium (V), selenium (Se), and copper (Cu), in the fish species Channa obscura and Lates niloticus from Alaro Stream in Ibadan, Nigeria. The research aimed to assess the levels of these metals in various organs of the fish and compare them against the World Health Organization (WHO) safety standards. Fish organs were pulverized and acid-digested, followed by analysis using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The findings revealed that mean concentrations of Ni, Se, and V in the fish exceeded WHO permissible limits of 0.07 ppm, 0.04 ppm, and 0.02 ppm, respectively. Notably, Ni levels in C. obscura peaked at 1.24 ppm in the gut, while the lowest concentration was 0.11 ppm in the intestine. The highest V concentration was observed in the fins of L. niloticus at 6.50 ppm. Se concentration in L. niloticus was highest in the intestine at 11.80 ppm. Cu concentrations in C. obscura showed an order of gills < gut < bone < liver < intestine < fins, whereas in L. niloticus, the order was liver < gills < bone < muscle < fins < gut < intestine. The study concludes that over 75% of the metal concentrations in these fish species exceed WHO safe limits, rendering them unsuitable for human consumption.