The distribution and abundance of coastal fish species in Asan Bay, Korea, were estimated from hydroacoustic surveyand net catches. Acoustic data were collected with 38 and 200 kHz from July to October of 2012, and converted to thenautical area scattering coefficient (NASC, m2/mile2) for 0.25 n？mile along ten transects. Japanese anchovy Engraulisjaponicus was the dominant specie in the net catches. The virtual echogram technique was used to distinguish E. japonicusfrom other species based on the differences in the mean volume backscattering strength (△MVBS) at 38 and200 kHz. Engraulis japonicus and other fishes are mainly distributed in the center channel and outer part of Asan Bay. E. japonicus tends to move from inner to outer Asan Bay in summer and fall. From NASC data, the target strengthand length？weight function of E. japonicus and other fishes were used to estimate the E. japonicus stock at 24.1？93.3tons, and other fish at 40.6？88.4 tons from July to October 2012. The estimated anchovy biomass compared well withthe cumulative catch weight from stow net catches. The hydroacoustic method offers an approach to understandingspatial/temporal structure and estimating the biomass of fish aggregations in coastal areas.