Histological changes in relation to accumulation and elimination of inorganic and methyl mercury in gills of Labeo rohita Hamilton.

L. rohita was exposed to identical concentrations of inorganic and methyl mercury (HgCl2 and CH3HgCl) and the gills were studied for mercury bioaccumulation and histological changes. In methyl mercury exposed group the mercury level in the gills continuously increased til the end of the exposure period whereas the level started decreasing from the day 30 onwards in the other group even though the exposure was continued for 60 days. Histological changes were similar in inorganic and methyl mercury treated fish except the higher intensity observed in the latter treatment. Under depuration for 15 days the clearance rate of accumulated mercury and subsequent histological recovery in the gills were less prominent in fish pretreated with methyl mercury.