Mercury is one of the most dangerous environmental pollutants, both in its elemental form and in chemical combination. When mercury is released into the environment it gets transformed into methyl mercury through microbial action. The methylation of mercury is a key step in the entrance of mercury into food chains. This methyl mercury is mercury in its most pernicious form. Methyl mercury bioaccumulates in fish and enters the human body when the fish is eaten. The objectives this study are: To quantify and assess the level of mercury in fish and crustaceans collected from Waterbodies in selected areas from different parts of West Bengal, five prominent markets in Kolkata; to try and arrive at a reasonable conclusion regarding the nature and extent of mercury contamination of fish, on the basis of analysing the results from the Laboratory; to make a risk assessment of mercury contaminated fish intake on the basis of detected contamination levels; and to suggest recommendations on the basis of the above results and analysis thereof.