Red Tail Catfish

Common name: Red-tailed catfish
Scientific name: Phractocephalus hemioliopterus
Synonyms: (none)
Size: Up to 4' (122cm)
Origin: South America (Amazon)
Tank setup: A huge tank is required, 8' long x 3' wide x 2.5' high (244 x 92 x 76cm) should probably be considered a MINIMUM for an adult. Minimal robust decor - it is advisable to have all heating and filtration outside of the tank, by using a sump filter or external thermofilter.
Compatibility: Very predatory, but not usually aggressive, keep with other
very large tankmates.
Temperature: 21-27oC (71-80oF)
Water chemistry: Fairly soft to slightly hard, pH 6.8-7.6
Feeding: Mainly carnivorous: in the wild, crabs, fish and also fruit are eaten. In the aquarium this can be replaced with cockles, mussels, whitebait and catfish pellets - moving onto larger fish etc as the fish grows.
Sexing: Unclear, males may have a deeper red tail and possess a more slender
shape.
Breeding: Unknown, and probably impractical in aquaria.
Comments: A truly magnificent fish, suitable only for the largest of home aquaria. Smaller juvenile specimens may be found for sale, but serious thought needs to be given to the huge home that will eventually be required. The fish pictured above was housed in a tank measuring 8' by 6' by 5' high!
Can you provide an enormous tank for a fish that may live for 20 years, require a large water change every week and consume a huge amount of food? If not, do not consider buying this fish. Many shops can't accomodate and re-sell grown-on red tailed catfish, and many public aquaria already have unwanted red tailed catfish and do not have room for more.

Source: http://www.thetropicaltank.co.uk/Fishindx/redtcat.htm