Investigation of acute toxicity of lead-manganese mixture to fish under laboratory conditions

The aim of this study was to investigate acute toxicity (96-hr LC50 and lethal concentrations) of waterborne metal mixture (Pb+Mn) for the fish, Catla catla, Labeo rohita, Cirrhina mrigala, Ctenopharyngodon idella and Hypophthalmichthys molitrix. The extent of metals bio- accumulation in fish body organs viz. gills, liver, kidney, fins, bones, muscle and skin at both 96-hr LC50 and lethal concentrations were also determined. The criteria of toxicity used during these experiments were mortality upon the 90-day old fish species. The tests were performed, separately, at constant pH (7), temperature (30°C) and hardness (200 mg L-1) of water with three replications for each test dose. The overall sensitivity of five fish species, determined in terms of LC50 and lethal concentrations, against metals mixture (Pb+Mn) varied significantly. Among five fish species, H. molitrix were significantly more sensitive to metals mixture with mean 96 hr-LC50 and lethal concentrations of 69.36±0.03 and 114.51±0.02, respectively. Regarding overall responses of five fish species for their ability to accumulate metals, kidney appeared as an organ to amass significantly higher amounts of metals, followed by that of liver while it was significantly least in fish muscles. Accumulation of the metals in fish body followed the general order: kidney>liver>fins>gills >skin>bones>muscle.