I don't often have opportunity to post info and photos on this fish since it is completely unsuitable for any aquarium except a public one (unless you have one the size of a room
), so I must take advantage and post a photo to show how these fish live.
The red tail catfish, Phractocephalus hemioliopterus,
occurs in the basins of the Amazon and Rio Orinoco, through every country in northern South America. It attains a length of more than a metre (5 feet). It lives in acidic waters that are very dimly lit. This is the only extant species in the genus, the others are now extinct; fossils of this species found in Venezuela are more than 6 million years old, so this fish has been here a long time, since before man.
There are a couple on display at the Vancouver Public Aquarium and Marine Science Centre in Vancouver, BC where I live, and these have been here more than 30 years now. I'm attaching a photo I took of one of them on a recent visit. The other (longest) fish in the photo is an Arapaima gigas, a true living fossil, and the largest freshwater fish in the world at more than 3 metres (12 feet). In the second photo, the "smaller" fish near the top are common Pacu, the largest species of characin at 3 feet in length. And in the back close to the substrate you can see a group of Leporinus fasciatus, another fish often available as 2-3 inch juveniles in stores but they neglect to warn customers that this fish grows to more than a foot in length and needs adequate space. It is an algae eating fish, and the habitat in the photos shows that though the light is very dim, algae (in the absence of aquatic plants) will flourish.
The "tank" housing these fish is a floor-to-ceiling wall of water behind glass that extends for some 25 feet in length. The habitat is authentic and represents one of the most common river aquascapes in South America.