Biotic and environmental factors affect Southwest Atlantic saltmarsh use by juvenile fishes

► Fish assemblages (FA) differed between the saltmarsh and the tidal the flat. ► Fishes of smallest sizes were more abundant in the saltmarsh. ► In the saltmarsh, the FA was correlated with the structure of benthic community. ► Environmental factors were not responsible for the differences in FA between areas. ► SW Atlantic saltmarshes function as refuge and feeding areas for juvenile fishes.