Scope of the environmental studies arrived when mankind faced serious threats regarding health due to changes in the environment. Some of the chemicals were determined as the indicator of environmental pollution, mercury is one of them. Hence in this research a new spectrophotometric method has been developed for the determination of mercury in liquid samples using silver nano-particles by the process of amalgamation. This research was dually emphasized on the production of uniformly sized and stable nano-particles of silver as well as the determination of mercury by them. Changes in the spectral characters of silver nano-particles by the addition of mercury were of the basic interest. Fish samples were sampled for the mercury content from Local Street and amalgamation was carried out. Results found out to be out of limits as per FDA and EPA. The current Lab-Scale work can be promoted on larger scale to provide sufficient betterment in the quality of fish food.