No abstract

Invasions of non‐native fish species are generally associated with human activities that violate historically insurmountable barriers to species on local and global scales. For Pterygoplichthys ambrosettii (Holmberg 1893), invasive to the upper Paraná River basin, informations about introduction and period of occupation are uncertain. Thus, aim of this study was to establish the invasion chronology and the establishment of this species in the Upper Paraná River basin, based on long‐term data (37‐year sampling), in addition to evaluating its current distribution. The results indicate that P. ambrosettii was first recorded in 1997 in the Itaipu reservoir and in 2000 in the Upper Paraná River floodplain. Currently, this species is registered in 118 localities in the basin, and the fact that several of these occurrences were recorded in locals that are not accessible through upstream migration suggests their origin from the aquarium hobby. This study elucidates when and where the invasion process of by P. ambrosettii began in the Upper Paraná River floodplain, and indicates that its broad non‐native distribution has exceeded the limits imposed by the geographical barriers.