Crenicichla semifasciata: Occurrence in the Upper Parana River floodplain, Brazil and First Record of Pughead Condition

This study aims to report the non-native occurrence of Crenicichla semifasciata in the Upper Parana River in the floodplain region, and the first record of the pughead condition in the species. C. semifasciata was described from the Paraguay River and there are already registers of individuals in the Upper Parana River basin. The register downstream, in the floodplain region, could be associated with aquarium trade, however, the most likely hypothesis is the anthropological introduction to exploitation in sport fishing. The introduction of C. semifasciata, as well as the discovery of the pugheaded specimen, indicate that humans are most likely interfering with the floodplain region, which is crucial to biological diversity in the Upper Parana River basin.