Experimental study of mercury accumulation in juvenile cyprinid fish Barbonymus schwanenfeldii and Tor tambroides, exposed through water and feed

. This paper reports the experimental study of mercury accumulation in juvenile cyprinid fish of Barbonymus schwanenfeldii and Tor tambroides. The juvenile cyprinids were exposed to mercury (Hg) through water (0.5 mg/L and 1.0 mg/L) and feed (0.5 mg/kg and 1.0 mg/kg) for 30 days. The behavioral response during feeding was monitored over the experimental period. The Hg concentration in the juveniles was analyzed after 30 days. The juveniles exposed to water contaminated with 1.0 mg/L Hg was found to disperse upon feeding suggesting an increase in vulnerability towards threats. This however was not observed in other treatments through feed and at 0.5 mg/L Hg. In terms of survival percentage, no statistical difference was deduced between treatments for both species. Among the two species, T. tambroides demonstrated greater affinity of accumulation; this is likely due to its biological behavior as a fast swimming species. The uptake of Hg (II) through gills was more pronounce than that through ingestion as the diffusion of Hg(II) was inhibited by the mucosal lining in the latter pathway. No significant correlation was established between size and Hg concentration in juveniles of both species