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Phractocephalus hemioliopterus

Red-tail Catfish




Present throughout much of the Amazon and Rio Orinoco basins in Colombia, Venezuela, Guyana, Ecuador, Peru, Bolivia and Brazil.


Occurs in a broad range of habitats from rapids to areas of flooded forest.

Maximum Standard Length

The largest specimen recorded by science measured 53.2″ (134cm), and weighed more than 40kg. Reputedly it can grow even bigger in nature.

Aquarium SizeTop ↑

Something in the region of 12′ x 8′ x 4′ (360cm x 240cm x 120cm) – 10,368 litres would be needed for a fully-grown fish, although even this wouldn’t provide space to cruise around as it would in the wild.


Strictly speaking, decor isn’t necessary for a tank containing an adult, provided the lighting is fairly dim. You can however add some large chunks of bogwood, beech branches or smooth rocks if you wish. Ensure that any such furnishings are too heavy to be moved around or secured to the tank in some way, and that there’s plenty of open swimming space. Juveniles enjoy hiding places in the form of bogwood, tangles of roots and branches, rock piles or lengths of plastic piping of a suitable bore.

Choice of substrate can be an issue, as most grades of gravel can either be swallowed or become caught in the delicate gills. Sand is ok, but don’t expect it to stay in one place. A layer of large, smooth pebbles is a better option. Alternatively you could leave the substrate out altogether, which would certainly make cleaning the tank an easier task.

A large and efficient biological filter is needed to cope with the amounts of waste produced by a fish of this size. If possible choose a sumptype arrangement, as this allows most of the equipment to be located outside the tank. A large specimen can easily destroy glass heaterstats, thermometers etc.

Water Conditions

Temperature: 70-79°F (21-26°C)

pH: 6.0-7.5

Hardness: 2-12°H


Quite an opportunistic feeder in nature, feeding on fish, invertebrates and fallen fruits. In captivity it relishes meaty items such as prawns, mussels, cockle, lancefish or earthworms. Larger specimens can be offered whole fish fillets (use white fish). Try to keep the diet varied or you may find it becomes too accustomed to a particular food and is reluctant to accept anything else. Also take care not to overfeed. It’s easy for predatory species to become overweight in captivity, especially when fed a high protein diet. This can lead to health problems in the long term. Feed every other day when juvenile but as the fish grows reduce the frequency. An adult specimen needs only a single meal per week at most.

It should not be fed the meat of mammals such as beef heart or chicken. Some of the lipids contained in these meats cannot be properly metabolised by the fish, and can cause excess deposits of fat and even organ degeneration. Similarly there is no benefit in the use of ‘feeder’ fish such as livebearers or small goldfish. Risks involved with feeding these include the potential of disease introduction.

Behaviour and CompatibilityTop ↑

Whilst it won’t hesitate to gobble any smaller fish, it’s actually quite peaceful and can be kept alongside other similarly-sized species in suitable surroundings. You’d need a tank approaching public aquarium size in order to do this, though. Most of the usual “tankbusters” are too small to avoid being eaten. Possible companions include Doradids such as Oxydoras niger or Pterodoras granulosus. If the tank is also very deep big characins and cyprinids could be added.
It’s territorial towards both conspecifics and other large Pimelodids, so should be the only fish of this type kept unless space is truly not an issue.

Sexual Dimorphism



Not thought to have been achieved in the hobby.

NotesTop ↑

Although this profile has been included for information purposes, we do not recommend keeping this species in the home unless you are one of the select few with the facilities available to house it for life. The aquarium dimensions quoted above should be considered an absolute minimum and in reality this fish requires a phenomenal volume of water if it is to be housed long term.

Unfortunately, the price of red-tails has fallen considerably in recent years and “kittens” are readily available at very low prices. As a result many public aquaria have large displays of adult specimens that have been “donated” by fishkeepers, often to the extent where they refuse to accept any more. A more depressing, but equally common scenario is that the fish are dumped into rivers and ponds when they outgrow their tank. In colder climates, they will obviously not survive, but populations exist in various states of the USA and several other countries as a result of releases by irresponsible aquarists.

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