Redtail Catfish - Phractocephalus hemioliopterus

The redtail catfish, known as pirarara in Brazil, is one of the most ubiquitous of the giant cats. It appears to have very few habitat limitations, just as happily living in acidic, blackwater lowlands streams as it is in alkaline highlands rivers. An extremely powerful fighter, redtails are known for a sustained, line-peeling initial run and the ability to find a tangle of submerged logs at the end. Their unique markings and bright coloration makes them unerringly easy to identify and their seemingly endless appetite makes them easy for anglers to engage.

Source: http://www.acuteangling.com/Catfish/catfish-redtail.html