Non-native fish species in Neotropical freshwaters: how did they arrive, and where did they come from?

The Neotropical region has the greatest taxonomic and functional diversity of fish in the world. However, this biodiversity has been threatened by the introduction of non-native species. Therefore, we present a systematic review of the literature concerning the introduction of non-native fish species in Neotropical freshwaters. We examine the origins of non-native fish species, as well as the invaded ecoregions and introduction vectors. Oncorhynchus mykiss, Salmo trutta, Cichla kelberi, and Oreochromis niloticus were the most frequent introduced fish species and rivers and reservoirs were the most studied freshwater ecosystems. Impoundments, aquarium trade, sport fishing, and aquaculture were recorded as the main vectors for the introduction of non-native fish species. Most of the studies were conducted in Brazil. The Upper Parana ecoregion exhibited the largest number of non-native fish species, of which the majority originated from the Lower Parana ecoregion. We noticed that the origins of non-native fish species are linked to their introduction vectors, as several non-native fish species arrive from areas near to where they are introduced, mainly by impoundment and sport fishing. On the other hand, species from regions outside the Neotropics are especially introduced by aquarium trade and aquaculture.