Heavy metals toxicity and bioaccumulation patterns in the body organs of four fresh water fish species

Various environmental pollutants, including metals can cause toxicological effects on aquatic animals especially fish species. Laboratory experiments were conducted to determine acute toxicity and bioaccumulation patterns of arsenic (As), nickel (Ni) and zinc (Zn) in 150-day old fish species (Labeo rohita, Cirrhina mrigala, Catla catla and Ctenopharyngodon idella), separately, in glass aquaria under constant water temperature (30 degree C), total hardness (300 mg L-1) and pH (7.5). Catla catla showed significantly (P less than 0.05) highest sensitivity to metals while L. rohita was least sensitive. Significantly variable accumulation of metals was observed in fish that followed the order: Zn greater than Ni greater than As. Among exposed fish species, Cirrhina mrigala exhibited significantly higher ability to amass Ni (146.8 plus minus 149.1 mug g-1) and Zn (243.0 plus minus 190.5 mug g-1), followed by Ctenopharyngodon idella, Labeo rohita and Catla catla at 96-h LC50. Liver showed higher tendency to accumulate Ni, followed by gills and kidney with significant differences while kidney showed higher tendency to accumulate As, followed by liver. Fins and scales exhibited significantly (P less than 0.05) least tendency to accumulate all the three metals. Accumulation of metals in different fish species is the function of their membrane permeability, which is highly species specific. Due to this reason different fish species showed different amount of metal accumulated in their bodies. This study also reveals that the metals, being conservative in nature have higher ability of biomagnifications.