Effects of Zinc and Lead Toxicity on the Growth
and their Bioaccumulation in Fish
M. Javed
Department of Zoology & Fisheries, University of Agriculture,
Faisalabad, Pakistan
Corresponding author: javeddr1@hotmail.com
Abstract
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.