Iguazu

Iguazu river flows through Argentina and Brazil. It is a significant Paraná River tributary. The Iguazu River is 1,320 kilometers long, with a 62,000-square-kilometer drainage basin. The Iguazu River is home to over 100 fish species, including several that have yet to be identified.

Catfish, characiforms, and cichlids make up the majority of the river's fish species. About 70% are endemic, which is mostly due to the falls, which serve as both a home for rheophilic species and a barrier between above and below. Large migratory fish known throughout much of the Paraná River Basin are naturally absent from Iguazu, with the exception of the endangered Steindachneridion melanodermatum in the lower section. In the river, there are about 30 introduced species, with roughly a third coming from other continents and the rest from elsewhere in South America. In the Iguazu River Basin, the unique Aegla crustacean is common.

Length: 820 miles (shared with Brazil)