EVALUATION OF SOME HEAVY METALS (LEAD, NICKEL, CADMIUM, AND CHROMIUM) IN FRESH AND SMOKED Clarias gariepinus AND Heterotis niloticus IN HADEJIA FISH MARKET, JIGAWA STATE, NIGERIA

Abstract

The evaluation of heavy metal concentrations, specifically lead (Pb), cadmium (Cd), nickel (Ni), and chromium
(Cr), in fresh and smoked fish species Clarias gariepinus and Heterotis niloticus was conducted to assess potential
health risks associated with fish consumption. A total of 36 fish samples, consisting of 18 each of the two species,
were procured from Hadejia fish market and subsequently brought to the laboratory for analysis. The
concentrations of the heavy metals were determined using standard analytical techniques following digestion of
the samples. Results indicated that smoked Clarias gariepinus exhibited Pb levels of 0.19 mg/kg, Cd at 0.18 mg/kg,
Ni at 0.16 mg/kg, and Cr at 0.18 mg/kg. In comparison, the smoked Heterotis niloticus displayed lower
concentrations with Pb at 0.13 mg/kg, Cd at 0.12 mg/kg, Ni at 0.14 mg/kg, and Cr at 0.16 mg/kg. Notably, fresh
Clarias gariepinus samples showed the highest Pb concentration in the gills (0.06 mg/kg), while fresh Heterotis
niloticus exhibited the highest Ni levels in the gills at 0.16 mg/kg. These results highlight the presence of heavy
metals in both fresh and smoked fish, underscoring the importance of regular monitoring for food safety and
public health, particularly in regions where fish consumption is prevalent. The findings call for further
investigation into the sources of these contaminants in aquatic environments.