Redtail catfish

The redtail catfish (Phractocephalus hemioliopterus), is a large species of South American pimelodid (long-whiskered) catfish. It is known in Venezuelan Spanish as cajaro; in Guyana, it is known as a banana catfish, and in Brazil it is known as pirarara, a fusion of words from the indigenous Tupi language: pirá and arara. It is the only extant species of its genus, Phractocephalus.

The redtail catfish is quite common in the aquarium trade, although it is often sold in its juvenile state, only measuring a few centimeters or inches at the time of sale. Additionally, they are often sold with little to no information for novice or uninformed buyers, with vague warnings, if any, regarding the fish's massive adult size. Thus, many redtail catfish are sold and subsequently purchased as very small specimens, soon outgrowing their new aquariums—something which makes them highly unsuitable for all but the largest, usually public, aquariums (or outdoor stock tanks, pools, ponds, lakes, etc). Unfortunately, many have likely been purchased when young, by uninformed shoppers, and later released by these same individuals when their true size and voracity became evident. In this way, humans have directly contributed to the species' spreading in areas outside of its natural range.

Hatchling (fry) and juvenile redtail catfish are most at-risk of being consumed by a range of predators, both aquatic and terrestrial. Larger adult specimens generally have little to fear, becoming voracious, opportunistic hunters themselves. Nevertheless, at any age or size, the redtail catfish is always at-risk of being consumed by humans, jaguars, giant otters, Orinoco and American crocodiles, and caimans, among other species.

Unlike other, bottom-dwelling catfish species, the redtail is an active swimmer, and does not lie in-wait on the river bottom to ambush passing prey. The redtail catfish is also not a picky eater, and is known for consuming anything that fits into its mouth. Meals range from other types of fishes, crustaceans, aquatic worms, and even amphibians, such as frogs, to fallen fruits, seeds and tree nuts, such as those of palms or Ficus. In captivity, it has been reported that the redtail catfish will eat dry cat food.

Distribution

The redtail catfish is native to the Amazon, Orinoco, and Essequibo river basins of South America, in Ecuador, Venezuela, Guyana, Colombia, Peru, Suriname, Bolivia, and Brazil. It is found only in fresh water, and inhabits larger rivers, streams, and lakes. They eat during the evening and night and stay motionless during the day. They are bottom-dwellers and move about quite slowly. Red-tailed catfish are territorial fish. Redtail catfish is also an invasive species in Malaysia; they are now found mostly in the Perak River and Pahang River.