The gilded catfish is the Amazon species known for a freshwater migration exceeding 5,000 km.
Also called the dorado catfish, Brachyplatystoma rousseauxii begins its life in the upper Amazon basin. Larvae drift downstream toward the estuary, where young fish grow before migrating back upriver. Adults eventually travel toward spawning areas in the Andean headwaters of Peru, Bolivia and Colombia.
Some individuals cover about 5,500 km from the mouth of the Amazon to their spawning grounds, making this one of the longest known migrations by a purely freshwater fish. The route is not a short seasonal movement: it can take five to six months, and broader life-cycle movements may span far more. Tambaqui and redtail catfish are also Amazonian fishes, but neither is the canonical answer to this record-setting migration question.