Over the years surface water quality of Pakistani rivers has been degraded. The current study aims to investigate the water quality and fish diversity at Rasul Barrage in the Jhelum River. A total of six sampling sites were assessed for pollution levels and fish fauna of the Barrage. Physicochemical parameters such as turbidity, biological oxygen demand (BOD), and chemical oxygen demand (COD) were deviating from the permissible limits of fresh water set by the U.S. Environmental Protection Agency (EPA), but meeting the criteria of NEQS, whereas pH, temperature, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), sodium, and chloride were below the permissible limits of NEQS, but the TSS level was above EPA standards. However, the concentrations of metals such as iron (2.62-3.98 mg L^-1), chromium (0.03-0.59 mg L^-1), and nickel (0.49-1.71 mg L^-1) were higher than the permissible limits for drinking and irrigation waters. In addition, a total of 35 fish species belonging to eight families were identified. Survey and result of study showed that concentrations of pollutants and non-stop fishing activities of commercial fish are the main reasons for the reduction of fish fauna. Two exotic fish species, Oreochromismossambicus and Ctenopharyngodon idella, were found to be abundant where population of native fish fauna numbers were being reduced. We concluded that the surface water quality is poor, as is evident from the higher concentrations of BOD, COD, and metals. Urgent measures are required to prevent such contamination and regular monitoring of water quality in the study area.