The catfish Genidens barbus (Siluriformes: Ariidae) is an anadromous species from South America. It has been classified as vulnerable in Argentina and Uruguay due to its complex life cycle, its restricted distribution in fresh or estuarine waters and the critical levels of fishery harvesting of this species. In this work, we report the occurrence of G. barbus in three great rivers, which could represent the evidence of an extension in its migration corridor in the Paraná River Delta (Argentina).