Cytogenotoxicity of Abattoir Effluent in Clarias gariepinus (Burchell, 1822) Using Micronucleus Test

The cytogenotoxic potential of abattoir effluent from Bodija, Nigeria, was investigated using micronucleus test in Clarias gariepinus. Fish was exposed to five different concentrations: 0.2, 0.4, 0.8, 1.6, and 3.1% of the effluent for 7, 14, and 28 days. Tap water and 0.02 mL/L of benzene were used as negative and positive controls, respectively. Physicochemical parameters and heavy metals were analyzed in the effluent in accordance with standard methods. After exposure, blood was collected from the treated and control fish and slides were prepared for micronuclei (MN) and nuclear abnormality evaluation in the peripheral erythrocytes. The effluent induced significant (p<0.05) increase in the frequency of MN in a time dependent manner. Similarly, the frequency of total nuclear abnormalities (blebbing, notch, bud, binucleation, and vacuolation) was higher in the exposed fish than the negative control. Electrical conductivity, nitrate, biochemical oxygen demand, chemical oxygen demand, arsenic, and copper analyzed in the effluent may have provoked the observed cytogenetic damage. The findings herein suggest the presence of clastogens and cytotoxins in Bodija abattoir wastewater which are capable of increasing genomic instability in aquatic biota.