摘要：Cadmium (Cd) is one of the most toxic, non-essential heavy metal and constitutes a real threat to fish because of its widespread occurrence in the aquatic environment. The present study is carried out to know the effect of calcium (Ca) in reducing the Cd bioaccumulation levels in the selected tissues of fresh water fish, Oreochromis mossambicus (Tilapia) exposed to Cd. The fish were exposed to cadmium chloride (CdCl ) at a sub lethal 2 concentration of 1/10th LC50/48 hrs i.e. 5ppm for 7, 15 and 30 days (d) time periods. After 15d Cd exposure, the fish were supplemented with trace element Ca (1ppm) and observed for again 7, 15 and 30d long sojourn. After the specified time periods, the test tissues like liver, kidney, muscle, brain and gill were isolated and tested for Cd bioaccumulation by Atomic Absorption Spectrophotometer (AAS – Schimadzu AA6300). There was a significant elevation in Cd concentrations in all the test tissues with increased period of exposure to the heavy metal. Maximum Cd accumulation was found in 30d Cd exposed fish kidney (22.353±0.41 ìg / gm wet wt. of the tissue) than the other tissues. However there was significant reduction in Cd bioaccumulation with Ca supplementation suggesting their vital role in heavy metal detoxification. Maximum decrease in Cd accumulation was found in 30d fish kidney (6.996 ± 0.284 ìg / gm wet wt. of the tissue) supplemented with Ca. Our findings clearly envisages that 30d Ca supplementation is more effective in reducing the Cd body burden when compared to other time periods in the fresh water fish, Oreochromis mossambicus
