Comparative Seasonal Assessment of Heavy Metals Bioaccumulation in Selected Tissues of Catfishand Tilapia from Zobe Dam, Nigeria

Bioaccumulation of persistent metals in aquatic organisms poses ecological and public health risks. ‎This study assessed cadmium (Cd), nickel (Ni), lead (Pb), and zinc (Zn) in gill, head, and muscle ‎tissues of Tilapia (Oreochromis niloticus) and Catfish (Clarias gariepinus) from Zobe Dam during dry ‎and wet seasons. Water samples were collected using composite techniques, while fish were ‎systematically sampled by weight and size. Samples were digested and analyzed using Microwave ‎Plasma Atomic Emission Spectrometry (MP-AES). Bioaccumulation factors (BAFs) were calculated ‎as tissue-to-water concentration ratios, revealing no significant seasonal and tissue-specific variations ‎‎(p > 0.05).‎ BAFs ranged from negligible (<1) to low-level accumulation (1–20). Estimated daily intakes (EDIs) ‎of metals were below oral reference doses. Hazard quotients (HQs) and hazard indices (HIs) were ‎consistently below 1, indicating no non-carcinogenic risk, while carcinogenic risk (CR) values for Cd, ‎Ni, and Pb were below the acceptable range (10⁻⁶–10⁻⁴), suggesting negligible lifetime cancer risk.‎ These findings indicate minimal metal accumulation in Zobe Dam fish and no significant ecological or ‎health risks, confirming that consumption of Tilapia and Catfish from this reservoir is safe.‎