Multidimensional world-wide developments in most areas have resulted into pollution of the environment. Municipal wastes, industrial effluents and heavy metal discharge have contaminated our aquatic ecosystem, as well as, the fish population and associated bacterial species in such environment. In the present study a fresh water fish, Channa punctatus, was exposed to Lead and further an opportunistic bacteria namely Aeromonas was isolated from various fish organs. This bacterium was further studied at various biochemical parameters to understand its characteristic features. This study will help shed some light on our environment and the pollution affecting it and will be of great help to all individuals interested in knowing our environment and especially to all the students of microbiology.