The redtail catfish, Phractocephalus hemioliopterus, is a pimelodid catfish. In Venezuela, it is known as cajaro, and in Brazil, it is known as pirarara, stemming from the Tupi language words pirá and arara. It is the only extant species of the genus Phractocephalus.The redtail catfish, Phractocephalus hemioliopterus, is a pimelodid (long-whiskered) catfish. In Venezuela, it is known as cajaro, and in Brazil,