Alien fish fauna of southeastern Brazil: species status, introduction pathways, distribution and impacts

Compiled inventories with information on the distribution, status and impacts of invasive alien species are essential for the study, management and monitoring of biological invasions. Despite their great importance, such studies are lacking for alien freshwater fish species in Brazil. Therefore, our aim was to improve the knowledge of the regional richness of alien species, leading to the closing of existing regional data gaps. We performed extensive bibliographic research and consulted with experts to update the list of freshwater alien fishes of six watersheds in southeastern Brazil (Upper Paraná, Paraíba do Sul, São Francisco, Mucuri, Jequitinhonha and Doce), and provided information on species invasion status, environmental impact category, pathway of introduction, origin and species taxonomic attributes. We compiled a list of 201 alien fish species introduced in the six watersheds (to 2019) through six pathways: aquarium trade, geographical barrier breach (after the flooding of a natural barrier by the construction of a hydroelectric power plant), aquaculture, stocking for sport fishing, live bait and biological control. The invasion status of the species varied among watersheds, and it was possible to characterize the impact of only 11 species. Our results show there are detailed data on the distribution and population status of alien fishes in Brazil, but also a lack of ecological studies on the impacts of such introductions. Research on the impacts of alien fish species on recipient ecosystems are urgently needed owing to the present high number and wide distribution of invasive species and lack of knowledge on the consequences of these invasions.