Size Matters: A Guide to Redtail Catfish Care and Keeping

Redtail catfish (lat. Phractocephalus hemioliopterus) got its name due to its bright orange tail fin. This is a good looking, but very large and predatory catfish, that yet is being kept in tanks. It can be seen on sale quite often as well. The redtail catfish grows very large even in small tanks. You’ll need a very roomy tank to keep this fish. It’s a predator, therefore everything it can swallow will be eaten and it can eat quite a lot.

Habitat in the wild

The redtail catfish (Phractocephalus hemioliopterus) belongs to the family Pimelodidae, which is commonly referred to as the long-whiskered catfish family. Pimelodidae is a diverse family of catfishes found mainly in South America, particularly in the Amazon and Orinoco river basins. Redtail catfish are known for their distinctive reddish-orange caudal (tail) fin, which gives them their common name.

Latin name of originates from Greek words ‘phraktos’ that means «a fence», and ‘kephale’ — «a head». It is not used for cooking because it’s not tasty. However, it is an object for sport fishing.

Redtail catfish inhabits Amazon, Essequibo and Orinoco river basins — from Colombia to Bolivia including Venezuela, Ecuador and Brazil. Also the fish was acclimatized in waters of Thailand and Florida state (USA). Redtail catfish are often found in the main river channels, where they take advantage of the abundant food supply, including smaller fish and other aquatic organisms. They tend to seek shelter among submerged logs, rocks, and other structures.

This is a demersal fish that prefers freshwater basins. The redtail catfish can be encountered is large and medium rivers, streams, lakes with sandy or muddy bottom. Its range of expansion is very wide – from fast flowing sections of rivers to immersed forest bogs. The fish feeds on fish, crabs and fruit. During the rainy season, rivers overflow their banks, creating extensive floodplains. Redtail catfish can be found in these flooded areas, where they can access new food sources and explore temporary water bodies.

Redtail catfish can also be found in oxbow lakes and other lentic environments connected to the main river systems. These lakes provide them with additional food sources and shelter. Shallow backwater areas and lagoons offer suitable habitats for redtail catfish, especially for younger individuals. These areas provide protection from strong currents and predators.



How big do red tail catfish get? Redtail catfish (Phractocephalus hemioliopterus) can grow to be quite large. As adults, they are considered one of the largest freshwater catfish species in the world. General length of the redtail catfish reaches 1,8 m (5 ft 11 in) and it weighs 80 kg (180 lb). In tanks tends to grow significantly smaller, but still its size is from 50 cm (20 inches) and to 100 cm (40 inches).

Their size makes them impressive and attractive to some aquarium hobbyists, but it’s essential to remember that they require a massive tank and careful care to meet their needs as they grow. Due to their potential size and specific requirements, redtail catfish are not suitable for small aquariums or inexperienced fishkeepers.


The lifespan of redtail catfish can vary depending on factors such as their habitat, availability of food, and the conditions in which they are kept. In the wild, redtail catfish can live up to 15-20 years or even longer if they are not subjected to significant threats or fishing pressure. However, due to their popularity in the aquarium trade, they are often harvested from the wild, which can impact their populations and overall lifespan.

In captivity, with proper care and a suitable environment, redtail catfish can also live for several years. However, they require a large aquarium with adequate filtration and regular maintenance to accommodate their size and ensure they remain healthy. Some reports indicate that well-maintained redtail catfish in captivity can live for over a decade.

It’s essential to provide redtail catfish with a suitable environment, a balanced diet, and proper care to help maximize their lifespan, whether they are in the wild or kept in captivity. Additionally, keeping redtail catfish in captivity should always be done responsibly and in consideration of their long-term needs.


The head is large, wide and flattened from top. The eyes are small, located at the top of the head. The fish has 3 pairs of barbels; one is on its maxilla and it is longer than other two pairs on its mandible.

The body is bulky and elongated. The dorsal is wide and tall. Fatty fin is small. Pectoral fins are long and wide. Anal fin elongated and has short base. The caudal fin is forked and very wide.


The back is brown, sides are yellow, pectoral, abdominal and anal fins are black, top of the dorsal (its bottom is black) and tail fins are orange-red. Due to such coloring the fish got its name. The abdomen is beige.

Scientific NamePhractocephalus hemioliopterus
Common NameRedtail catfish
FamilyPimelodidae (Long-whiskered catfish family)
DistributionNative to the Amazon and Orinoco river basins in South America
HabitatRivers, floodplains, lakes, backwaters, swamps, and marshes
SizeCan grow up to 4-5 feet (120-150 cm) in length
WeightAdult individuals can weigh up to 55-110 lbs (25-50 kg) or more
ColorationPredominantly dark gray or black body with a distinctive reddish-orange tail fin
WhiskersPossesses long, sensitive whiskers (barbels) that help it sense its environment and prey
BehaviorMostly nocturnal, active during the night, and a voracious predator
DietOmnivorous, feeds on a variety of prey, including fish, crustaceans, and plant matter
LifespanCan live up to 15-20 years in captivity, lifespan in the wild is uncertain
Conservation StatusNot evaluated globally by the IUCN (International Union for Conservation of Nature)
Aquarium ConsiderationsPopular in the aquarium trade but requires a very large tank due to its large size
Conservation ConcernsOverfishing and habitat destruction in the wild threaten their populations

Difficulties in keeping

The redtail catfish is undemanding, quite nice and active. But. This is a monster, that can grow to be a huge fish. Quite often aquarists buy it because of its unusual appearance and then they start to notice that other fishes in a tank start to disappear.

At that the redtail catfish grows very fast. When its owner gets who eats other tank dwellers, he tries to get rid of the pet. However, there are not that many volunteers who want to have it.

Care and keeping in the tank

Tank size

The redtail catfish is extremely challenging in terms of keeping due to its size and requirements as for the available space to swim. Redtail catfish require very large tanks due to their massive size and rapid growth rate. As juveniles, they might initially seem suitable for smaller aquariums, but they quickly outgrow such setups. Keeping them in a small tank is not only detrimental to their health and well-being but also impractical in the long run. Young species can live in smaller tanks, but if you don’t provide them with a tank of corresponding volume as they grow, the fish will die early.

That’s why recommended tank volume should be at least 1000 liters (220 gallons). For one adult redtail catfish, you would ideally need an aquarium that holds a minimum of 1,000 gallons (3,785 liters) of water. However, a larger tank, such as 1,500 gallons (5,678 liters) or more, is preferable to offer ample swimming space and reduce stress on the fish.

Redtail catfish are highly active swimmers and can reach lengths of up to 4-5 feet (120-150 cm) or more in captivity. In such large tanks, you should also ensure that the filtration system is powerful enough to handle their waste and maintain water quality.

It’s crucial to consider the long-term commitment and costs associated with keeping a redtail catfish. These fish can live for many years when provided with proper care and a suitable environment. Before acquiring a redtail catfish, make sure you have the space, resources, and dedication necessary to meet their unique requirements and ensure their well-being.

Water parameters

Maintaining proper water parameters is crucial for the health and well-being of redtail catfish (Phractocephalus hemioliopterus) in both the wild and in captivity. Redtail catfish are hardy fish, but they do require specific water conditions to thrive. Here are the recommended water parameters for redtail catfish:

  1. Temperature: Redtail catfish prefer water temperatures between 72°F to 82°F (22°C to 28°C). Keep the water temperature stable within this range to avoid stressing the fish.
  2. pH Level: The ideal pH range for redtail catfish is slightly acidic to neutral, with a pH level between 6.5 to 7.5. Avoid extreme pH fluctuations, as these can be harmful to the fish.
  3. Ammonia and Nitrite: Both ammonia and nitrite are toxic to fish. Make sure the aquarium is cycled and properly established to maintain low levels of ammonia and nitrite (ideally at 0 ppm).
  4. Nitrate: Nitrate is a byproduct of the nitrogen cycle and should be kept at a low level to prevent stress on the fish. Aim to keep nitrate levels below 40 ppm and ideally lower.
  5. Hardness: Redtail catfish can adapt to a range of water hardness levels. Aim for a general hardness (GH) between 4 to 15 dGH and a carbonate hardness (KH) between 2 to 10 dKH.
  6. Water Changes: Regular water changes are crucial to keep the water quality high. Aim to perform partial water changes (10-20% of the tank volume) at least once a week to remove accumulated toxins and waste.

Tank decor

Having shelters in a tank is a must, since the fish will spend most of its time there, especially when it grows older. The fish will guard its shelter from other tank mates invasion. The redtail catfish likes all kinds of shelters and when it is young it can easily get into any cave, but the large adult fish species has to just lie down over some snag or log in a tank.

The tank bottom substrate should be dark colored. As for the tank decorations – one or two snags will do. You should fix them to the bottom since adult species may break the tank glass with such a snag. Don’t use stones as tank decorations for the same reason.

As for the tank plants, they will grow and be ok only when the fish is small. Some time later the catfish may just root them away. Putting tank plants into flower pots won’t help in this case as well.

The redtail catfish may live at Spartan tank conditions. Moderate lighting, some snags and large stones as shelters – this is all the fish needs.


Redtail catfish are large, bottom-dwelling fish that prefer a soft and sandy substrate in their aquarium. A suitable substrate for redtail catfish should mimic their natural habitat and provide them with a comfortable and safe environment. Here are some options for the substrate that are commonly used for redtail catfish:

  1. Fine Sand: A soft, fine sand substrate is an excellent choice for redtail catfish. It allows them to sift through the substrate in search of food and provides a natural feel for their sensitive barbels (whiskers). Sand also helps to maintain good water quality by promoting beneficial bacteria growth.
  2. Smooth Gravel: If you prefer using gravel, choose smooth gravel without sharp edges. Rough gravel can potentially harm the catfish’s barbels and may not be as comfortable for them to move around.
  3. River Rocks: Large, smooth river rocks can be used to create a more natural-looking substrate. These rocks can also provide hiding spots and shelter for the catfish.
  4. Bare Bottom Tank: Some keepers prefer a bare bottom tank for easier maintenance and cleaning. However, this setup may not offer the most natural environment for the catfish and may require additional hiding spots and decorations.

When selecting a substrate, it’s essential to avoid anything that could harm the fish, such as sharp or jagged materials. Additionally, make sure the substrate is thoroughly cleaned before adding it to the tank to prevent any potential contaminants or pollutants.


However, powerful canister filter is a must, because the redtail catfish produces a lot of waste. All possible tank equipment has to be put outside the tank, since the fish easily destroys thermometers, sprayers etc. The fish gets used to its owner very quickly and lets him stroke it.


Redtail catfish are omnivorous predators with a diverse diet. Their diet consists of various prey items found in their natural habitats. Here are some of the common food sources for redtail catfish:

  1. Fish: Redtail catfish are piscivorous, meaning they primarily feed on other fish. They are opportunistic predators and will eat smaller fish that they can overpower. In their natural environment, they may consume a variety of fish species.
  2. Crustaceans: They also feed on crustaceans such as crabs, crayfish, and shrimp. These small invertebrates provide an additional source of protein in their diet.
  3. Insects: Insects and their larvae are part of the redtail catfish’s diet. They may consume aquatic insects like beetles, dragonfly nymphs, and small aquatic bugs.
  4. Small Mammals and Birds (Rare Occasions): In some cases, particularly in larger individuals, redtail catfish have been reported to consume small mammals or birds that come near the water’s edge.

In captivity, redtail catfish are usually fed a diet of high-quality pellets, frozen or live fish, shrimp, and other protein-rich foods. It’s essential to offer a varied diet to ensure they receive all the necessary nutrients. Keep in mind that as they grow, redtail catfish require larger prey items and more substantial meals to meet their dietary needs.

When keeping redtail catfish in an aquarium, it’s crucial to provide appropriate feeding portions and avoid overfeeding, as they can be voracious eaters and may become obese if fed excessively. Proper nutrition and a balanced diet are essential to their overall health and well-being in captivity.

Tank mates

Fish has a large mouth and good appetite, that’s why any small sized tank mates will be eaten. This catfish gets along well with the fish species of its size, but there are almost no tank fishes of such size. Any other fish that is sufficiently smaller will be treated as food.

This fish guards its territory and may demonstrate aggression towards its relatives or catfish of other kind, that’s why don’t keep them together (though it is hardly ever possible). Keep just several adult fish species in a tank or just one of them.

It is better to observe this catfish in public tanks, where in a volume of many tons capacity there is a whole community of Amazon selva. As a rule in such tanks tank mates are black pacu, giant gourami, iridescent shark or large sized armored catfishes (sailfin pleco, common pleco).

Gender differences: male vs female

The redtail catfish doesn’t have any pronounced gender dimorphism. It’s important to note that visually determining the sex of redtail catfish can be unreliable, especially when they are still young or not yet sexually mature. For a more accurate determination of the sex, experienced aquarists or biologists might use techniques such as ultrasound or endoscopy to examine the internal reproductive organs.

Sexual Dimorphism in Redtail Catfish:

  1. Size: In some cases, females might grow slightly larger than males. However, this difference in size is not always consistent and can vary between individuals.
  2. Body Shape: Adult females may have a fuller body shape, especially when they are carrying eggs or are in the breeding season. Males might appear slightly more streamlined.
  3. Genital Papilla: When redtail catfish reach sexual maturity, females may have a more rounded genital papilla (an external projection near the anal opening), while males might have a more pointed or elongated genital papilla. However, this difference can be subtle and challenging to identify without experience.
  4. Behavior: During the breeding season, males might exhibit more territorial and aggressive behaviors as they compete for females.

In a typical home aquarium, sexing redtail catfish can be challenging, and often, their sex remains unknown unless they are part of a breeding program or examined by professionals with appropriate techniques. Additionally, sexing fish can be stressful for them, so it’s essential to prioritize their well-being and ensure they have a suitable environment regardless of their sex.


For obvious reasons in a home aquaria breeding this catfish is impossible and is not as commonly done as breeding some other species of aquarium fish. Redtail catfish are large, predatory fish, and they require specific conditions and careful management for successful breeding. Here are some key points to consider if you are interested in attempting to breed redtail catfish:

  1. Tank Size: Redtail catfish can grow very large, so you will need an enormous tank to house a breeding pair comfortably. A tank with a capacity of several thousand gallons would be more appropriate to accommodate their size and provide adequate space for breeding behavior.
  2. Water Quality: Maintaining excellent water quality is crucial for successful breeding. Regular water changes and efficient filtration are necessary to keep the water parameters stable.
  3. Environment: Create a suitable environment that mimics their natural habitat. Provide hiding spots like caves or large tubes where the female can lay eggs and the male can guard them.
  4. Pairing: Introduce a compatible breeding pair into the breeding tank. Determining the sex of redtail catfish can be challenging, and it is often difficult to identify males from females until they are mature enough for breeding.
  5. Conditioning: Prior to breeding, condition the fish with a nutritious and varied diet. This will help improve their health and reproductive readiness.
  6. Spawning: Redtail catfish are egg scatterers, meaning they lay eggs that are fertilized externally. The female will lay eggs, and the male will follow, fertilizing them. After spawning, remove the adult fish from the breeding tank to protect the eggs.
  7. Egg Care: The eggs should hatch within a few days. Provide gentle aeration and ensure the water parameters remain stable to increase the chances of successful hatching.
  8. Fry Care: Once the eggs hatch, the fry are generally quite large and can consume small live foods like baby brine shrimp. Gradually transition them to larger foods as they grow.

Breeding redtail catfish is a complex and challenging endeavor, requiring a significant commitment of time, resources, and expertise. If you’re not an experienced aquarist or do not have access to the necessary facilities, it may be best to leave breeding redtail catfish to experienced fish breeders and focus on providing them with a suitable and comfortable environment in captivity. Remember that these fish can grow very large, and proper long-term care should be considered before acquiring them.