The present investigation was carried out to evaluate the magnitude of physico-chemical parameters in river system (namely river sone, river koshi near Saharsa, river Ganga at Buxar, Patna, Mokama and Barh) with a view to assess its suitability for fish growth and other purposes. The parameters studied were pH, temperature, D02, salinity and soluble or suspended inorganic constituents. DO2 of these sites have significant differences. Barh site of river Ganga was most suitable for fish growth and development while Buxar was most unfavourable site as evidenced by faunistic studies. The details have been discussed in this paper.