Red Tail Catfish - Phractocephalus Hemioliopterus

Red Tail Catfish | Phractocephalus hemioliopterus, the Amazon’s Giant Showpiece

The Red Tail Catfish (Phractocephalus hemioliopterus), also called the RTC or Pirarara, is a giant Amazonian catfish with a glossy dark body, a bold white belly and cream-white band, and a flaming orange-red tail that gives it its name. A broad head and wide mouth give it a prehistoric look. It is also an active, curious swimmer and not a lurking bottom ambusher, and it learns to recognise the person who feeds it.

Native to the Amazon and Orinoco river basins of South America, the Red Tail is a spectacular fish for aquarists with the space and resources for it. It is also commonly bought on impulse as a small juvenile without the adult size in mind. Please read the size section below before purchasing.

Before You Buy: Adult Size and Commitment

Red Tail Catfish are sold as small juveniles and grow quickly, often 1–2 inches per month in their first year, reaching around a foot within the first year and 2 feet or more soon after. Adults in captivity typically reach 3–4 feet (90–120 cm), and wild fish can grow larger still. They can live for 15–20 years.

A juvenile can be housed temporarily in a large aquarium, but an adult needs a genuinely enormous system: at least 1,000 gallons, with many sources recommending far more, or a very large pond or purpose-built enclosure. The water alone in a system that size weighs thousands of pounds, so the floor and building must be able to support it. If you do not have a realistic plan for housing the adult fish, this is not the right species for you. We are always happy to talk through options before you buy.

Red Tail Catfish Care Guide

Care at a Glance

• Scientific name: Phractocephalus hemioliopterus
• Also known as: Red Tail Catfish, Redtail Catfish, RTC, Pirarara
• Origin: Amazon and Orinoco river basins, South America
• Adult size: 3–4 feet (90–120 cm) in captivity, with larger sizes possible
• Minimum tank size: juveniles can be housed temporarily in a large tank, with adults needing 1,000+ gallons or a large pond
• Temperature: 70–80°F (21–27°C)
• pH: 6.0–7.5
• Hardness: soft to moderately hard water
• Lifespan: 15–20 years with good care
• Keep one per tank

Red Tail Catfish Tank Setup

Plan for the adult from the beginning. Use a soft sandy substrate, as these fish spend much of their time near the bottom, and keep the layout open with a few large, stable pieces of driftwood or smooth rock for cover. Avoid sharp décor, which can injure them. Red Tails are large, heavy-bodied, and waste-heavy, so powerful filtration is essential, with a sump-style system the usual choice at larger sizes. Water changes should be regular and substantial to keep water quality high. A heavy, secure lid is needed, as an excited adult can easily knock it aside.

Feeding Your Red Tail Catfish

Voracious predators that will eat almost anything that fits in their mouth. Feed a varied, high-quality diet of large sinking carnivore pellets, with prawns, whole fish, mussels, and earthworms as supplements. Juveniles feed frequently, while adults generally need only a couple of meals per week. Avoid overfeeding, as these fish will eat as much as they are given and quickly foul the water.

Temperament and Tank Mates

Red Tails are territorial and best kept singly. They will eat any fish small enough to swallow, which includes most common community fish, so tank mates must be large and robust. Suitable companions in a very large system are other big, non-aggressive fish of comparable size, such as Pacu, large Silver Dollars, or similar giants. Mixing them with smaller or more aggressive fish does not work in the long term.