Our study demonstrated that heavy metals like Mercuric Chloride are very harmful for the fish health. Kidney plays a very important role in fish as they are the site for the removal of toxicity and excretion of wastes. The rising amount of Mercury in fresh water bodies coming from different sources like factories, tanneries and different industries is proving a big threat for aquatic life and ultimately effecting human health. Hematological studies showed that mercury has very toxic effect on the blood of the fish. In mercuric chloride treated fishes there was significant decrease in HGB count, GRAN count and LYM as compared to control.