Genotoxicology: Single and Joint Action of Copper and Zinc to Synodontis clarias and Tilapia nilotica

The genotoxicity of copper, zinc and their binary mixture was examined in Synodontis clarias and Tilapia nilotica using the sensitive micronucleus assay in fish genome. Increased formation of the micronuclei were observed in all the three concentrations studied (0.25LC50, 0.125LC50 and 0.0625LC50). The frequency of micronuclei was observed to increase heavily (p 0.05) when the fish species were exposed to binary mixture of the heavy metals. Individual metal (Cu and Zn), acting alone, produced significant (p 0.05) levels of micronucleated erythrocytes in both species. After 96-hour recovery in clean water of the fish species exposed to the binary mixture of the heavy metals, the levels of micronuclei in Tilapia nilotica decreased (p 0.05) while the levels in Synodontis clarias displayed no meaningful decrease (p 0.05) at the highest and lowest concentrations studied. Synodontis clarias was numerically observed to exhibit higher incidence of micronuclei in the sampled blood than Tilapia nilotica.