LAUSR

Abstract Aquatic pollution may continue to deepen following the emergence of new class of toxicants. The present study investigated the effect of water-soluble fraction of burnt tire-ash on Clarias gariepinus. The fish were exposed to sublethal doses; 0.00 g/L, 2.24 g/L, 1.12 g/L and 0.56 g/L of tire-ash solution, representing 1/5, 1/10 and 1/20 of 11.2 g/L median lethal concentration (96 LC50), for 28 days, followed by 14 days recovery trial. Biological sampling was done on exposure day 1, 14 and 28, and on day14 recovery period for biochemical analysis such as the liver and gill Na+/K+ and Ca2+-ATPase, serum immunoglobulin (IgM) and brain acetylcholinesterase (AChE) of the experimental fish. Also, body biomass and behavior were evaluated. The behavioral responses exhibited by the fish to BTA exposure include reduced feeding, hypoactivity, air gulping and skin discoloration, which was observed to be concentration dependent. The body weight of 2.24 g/L and 1.12 g/L BTA-exposed fish decreased significantly than 0.56 g/L exposed fish and the control. Furthermore, findings revealed evident induction of Na+/K+ and Ca2 +-ATPase activities in both tissues, elevation of serum immunoglobulin content and inhibition of AChE activity in the brain of the exposed fish relative to the control. However, it was also observed that the biochemical parameters normalized after the recovery period. In conclusion, water-soluble fraction of burnt tire-ash produced toxicological effects in the experimental model, hence the present study provides the ecotoxicological insight of tire ash.