The present research work includes an assessment of the physico-chemical parameters, biological conditions and fishery status of the Tungabhadra Reservoir, Hospet town, Bellary. The physico-chemical parameters, phytoplankton, zooplankton and fish fauna were studied in five topographically different sampling stations across the Tungabhadra Reservoir for the stretch of 58 Kms by water route. The scientific appraisal of plankton community provided information necessary for understanding of growth and abundance of fin-fish population. In the present study abundance and diversity of four major phytoplanktonic groups represented by Desmidaceae, Chlorophyceae, Cyanophyceae and Bacillariophyceae were undertaken. It is clear from the results that the reservoir is mesotrophic and aging towards eutrophication especially in the upstreams. Hence measures should be taken to prevent influx of domestic sewage, entry of debris from the anthropocentric activities, industrial effluents from neighborhood and controlled disposition from the neighboring farm lands. Since the TBR is a joint venture operation of Hyderabad-Karnataka, yearly scientific documentation is useful for assessing its productivity.