Effects of Zinc and Lead Toxicity on the Growth and their Bioaccumulation in Fish

This study evaluated the impacts of chronic exposure of waterborne zinc (zn) and lead (pb) on the growth and their bioaccumulation in three fish species viz. catla catla, labeo rohita and cirrhina mrigala. three fish species responded similarly for their feed intakes while weight increments and feed conversion efficiency (fce) varied significantly due to zn and pb exposures. younger fish were significantly more sensitive to metallic ion toxicity. chronic exposure of both zn and pb (at 1/3rd of lc50) to the fish caused significantly lesser gain in weight, feed intakes and fce than that of control (un-stressed) fish. amongst 9 age groups, 330-day fish exhibited significantly better growth in terms of weight gain and feed intake than the other age groups. both zn and pb bioaccumulations varied significantly among fish organs while the patterns of their bioaccumulation did not vary significantly within three fish species. fish liver and kidney accumulated significantly higher zn and pb during chronic exposures. however, zn accumulation was significantly more than that of pb in the fish body. amongst three fish species, labeo rohita exhibited significantly higher tendency to accumulate zn while catla catla amassed higher pb in its body. the bioaccumulation of both zn and pb was positively dependent upon fish age and exposure concentration of metals. zn bioaccumulation in fish body followed the order: liver>kidney>skin>gills>scale=muscle while that of pb was: kidney>liver>gills>skin>muscle=scales.