Redtail Catfish 101: Size, Care, & Tank Mates

The redtail catfish is a massive freshwater fish that only the most experienced aquarists should attempt to keep.

Despite that, there are a lot of people who think that these fish are much more manageable to keep in captivity than they are.

So we’re here to set the record straight.

This guide on redtail catfish care will give you an honest look at what it really takes to keep this fish as a pet and help you decide if it’s something you’re ready for.

Species Summary

The redtail catfish (scientific name: phractocephalus hemioliopterus) is native to north-most South American countries. The countries it can commonly be found in are Colombia, Brazil, Peru, Venezuela, Ecuador, Guyana, and Bolivia.

It spends its time in freshwater river basins (the Amazon and Orinoco primarily), streams, and lakes looking for anything it can eat. These fish aren’t picky!

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A redtail catfish swimming in a large tank

They have a bit of a reputation in the countries it occupies due to a combination of their size and mythical stories of their aggression. There is a lot of respect for the redtail catfish in South America.


The average lifespan of a redtail catfish is around 15 years in captivity. In the wild they have been known to live longer, but there isn’t a significant amount of data on that.

Since these fish need very specific requirements when it comes to their care, it’s very common for underprepared aquarists to shorten their lifespan significantly. Any subpar care for such a large fish will quickly shave years off its life.


The redtail catfish has a very classic “catfish” look to it. The barbels (long whiskers) it has are quite large and impossible to miss. They tend to stick straight outward no matter if the fish is swimming fast or not.

The main color of their body is dark grey with a smattering of faint dots stretching over this part of their body. 

The colors of a redtail catfish

The underside of their heads is white and extends back roughly to where their pectoral fins begin. This white area usually travels up over the top of their pectoral fins and continues all the way to the base of their caudal fins.

Their caudal fins are red as well as the top third of their dorsal fins. This is where they get their rather straightforward name.

Redtail catfish have a rather thick body that tapers off a bit toward their tail. Like a lot of freshwater catfish, their underbelly is quite flat, especially underneath their head.


The average size of a redtail catfish in captivity is around 3-4 feet in length. In the wild, this can be closer to 5 feet.

It’s important to understand just how massive this is, and what that means for anyone who wants to keep one in a home aquarium. This means that the minimum tank size is going to be astronomical just to make them relatively comfortable.

Author Note: There’s a lot of misinformation about redtail catfish online. One of the more concerning trends is that many new aquarists think that keeping these fish in tanks at an early age will significantly stunt their growth. This is outright wrong because even though it will definitely stunt their maximum length a bit, they’ll still likely hit 3 feet at least.

Redtail Catfish Care

If you want to give redtail catfish care a shot there are some things that you simply cannot compromise on. With such large and aggressive fish the stakes are always a lot higher and mistakes are punished more as well.

Tank Size

The minimum tank size for an adult redtail catfish is around 1,500-2,000 gallons (yeah). This will give them enough room to swim around and be active without feeling cramped and unhappy.

This huge tank size is obviously quite a lot compared to most freshwater home aquariums. This is where most potential owners typically call it quits because it’s not viable for almost everyone.

Don’t think that you can compromise with something like a 1,000-gallon tank either. This is not nearly enough. Redtail catfish are fish that don’t do well with half measures.

Water Parameters

The water parameters are obviously very important as well. Even though redtail catfish are considered hardy, we always recommend doing everything you can to make sure the water situation is as good as it can be.

  • Water temperature: 68°F to 80°F
  • pH levels: Somewhere between 6 and 7.5 is fine, but staying below 7 is ideal.

Maintaining the optimal water parameters can be challenging with such a large tank. A lot of the people who attempt to keep this fish in their home aquarium find that they spend most of their time on this (at least initially).

It’s a very different experience trying to heat a tank that’s almost 2,000 gallons compared to a tank that’s only 20!

Author Note: Due to the amount of food redtail catfish comsume they also create a lot of waste. This presents another challenge when it comes to maintaining water quality.

What To Put In Their Tank

Not much!

Redtail catfish love to eat, and that is not exclusive to animals and plants. They will chow down on random items like driftwood, rocks, and gravel too.

This means the ideal tank set up for them is a very large tank, with very little inside it. They don’t require a bunch of decorations or hiding places (they’re quite confident fish) and will likely tear up or consume whatever they find.

Redtail catfish in a sparse tank

This means that you also will want to limit your substrate to a sandy variety if that. This is also something they might nibble on over time so it’s recommended that a substrate-free tank is probably best for them. This obviously has aesthetic downsides, but it’s best for the fish.


The easiest thing when it comes to redtail catfish care is their lighting situation. These fish don’t need much when it comes to light, so a standard lamp will do the trick.

Food & Diet

Redtail catfish love to eat. Period.

You can pretty much feed this fish whatever you want and they’ll scarf it down. However, that doesn’t mean it’s the right thing to do.

Just like any fish, they have certain dietary and nutritional requirements that you’ll need to hit if you want them to live as long as possible.

In their natural habitats these fish will eat worms, smaller fish, insects, and random vegetation they come across. You’ll want to keep this in mind when coming up with their diet in captivity.

Some of the recommended live food choices for an optimal redtail catfish diet are:

  • Small fish
  • Worms
  • Shrimp
  • Cut up meat

There are also a lot of great pellet and frozen food options that you can use to provide a good nutritional baseline. Remember that with pellet food you’ll want to make sure it’s a sinking variety so it makes its way down to where they spend time in the tank.

Behavior & Temperament

The behavior and temperament of redtail catfish can vary depending on who you talk to. Some people will say they’re hyper-aggressive, and others will say they’re actually rather peaceful.

In our opinion, this is mostly influenced by their tank setup as well as what you define as aggressive. If you consider their natural predatory instincts to be aggressive, then this fish would quality.

We don’t think that’s a very fair label though, because they’re just doing what they know. We would define aggression as non-hunting actions that can harm another fish. While in the right circumstances redtail catfish can display this behavior as well, it’s far less likely.

The phractocephalus hemioliopterus at night

As far as their normal mannerisms go, these fish will spend most of their time roaming around the bottom half of the tank. This is normal catfish behavior and won’t change regardless if you house them with other fish or not. This is something you’ll definitely need to keep in mind when it comes to tank mates (more on that in the section below).

Redtail Catfish Tank Mates

Due to their size and the fact that they eat smaller fish in the wild, picking tank mates for a redtail catfish can be very challenging. The primary issue is that most typical freshwater aquarium fish are smaller than the redtail (because they’re massive).

This means if you’re going to attempt to find redtail catfish tank mates the main factor you should consider is size. If it’s smaller than your redtail it’s not viable.

Pretty much anything nonaggressive that’s the same size or larger can work if they’re introduced to each other early on.

For the most part, redtail catfish owners tend to keep these fish by themselves. There are a lot of things to consider and when you add more large fish to the equation it brings the minimum tank size up even more.

Our recommendation would be to avoid tank mates for the sake of convenience and peace in the tank. Redtail catfish can be so hungry that you never know what they’ll try to chomp down on!


As you can probably tell, caring for redtail catfish is not for everyone. In fact, we would say it’s not for most aquarists.

You need a healthy dose of experience, space, and resources to make it happen.

If that describes you then feel free to go for it! Keeping these fish is definitely not impossible and will be quite rewarding once you put the time in.

If you’re someone looking for a hassle-free freshwater fish that doesn’t require having a swimming-pool sized tank in your home, you should probably pass.

We love these fish though and would enjoy hearing any stories or feedback from redtail catfish owners. Caring for such large fish is a very different experience, so it’s always fun to learn more about!

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