Ever increasing consumption of fossil fuel and large scale deterioration of environment are mandating employment of renewable fuels. Researchers all over the world are experimenting on variety of alternative fuels for meeting future energy demands. Biodiesel is one of the most promising alternative fuels due to lower CO, HC and PM emissions. However, NOx emissions are increased in case of biodiesel in CI engine. The present study focuses on evaluation of performance and emission characteristics of a medium capacity diesel engine on blends of fish oil biodiesel and diesel blends employing EGR. Fish oil was transesterified with methyl alcohol to produce methyl ester. B20 blend of biodiesel was used since it balances the property differences with conventional diesel, e.g., performance, emission benefits and cost. Further, B20 blend can be used in automotive engines with no major modification. NOx formation takes place when combustion temperature is more than 2000K. Exhaust gas recirculation (EGR) is an effective method for reducing NOx emissions in CI engines because it reduces the flame temperature and the oxygen concentration in the combustion chamber and therefore was employed in the present research work. The EGR rates selected in the study were 5%, 10%, 15% and 20%. Performance and emissions characteristics of fish oil biodiesel blend (B20) with different EGR rates were measured and compared with baseline data of diesel. The result shows that adaptation of EGR with B20 reduces NO emissions without any significant penalty on smoke opacity or BSEC. EGR rate of 15% was found to be effective to reduce NOx emission substantially without deteriorating engine performance in terms of thermal efficiency, BSEC, and emissions.