About 100 fish species are native to the Iguazu River and several undescribed species are known. Most fish species in the river are catfish, characiforms and cichlids. About 70% are endemic, which to a large extent is linked to the falls, serving both as a home for rheophilic species and isolating species above and below. This also means that, with the exception of the threatened "Steindachneridion melanodermatum" in the lower part, large migratory fish known from much of the Paraná River Basin are naturally absent from Iguazu. Almost 30 introduced species are found in the river where about one-third originate from other continents (such as carp, largemouth bass, tilapia and African sharptooth catfish) and the remaining from elsewhere in South America (such as dorado, "Cichla kelberi", pacu, "Brycon hilarii", "Prochilodus lineatus" and "Odontesthes bonariensis").