The redtail catfish is a freshwater fish of the Pimelodidae family. These fish have grayish-brown bodies with red tails, long whiskers, and large mouths. Redtail catfish are difficult to care for because of their enormous size and predatory nature.
These catfish are popular with experienced aquarists who have extremely large tank setups and find the challenges involved in the fish’s care rewarding.
TABLE OF CONTENTS
Redtail Catfish Facts & Overview
Redtail catfish (Phractocephalus hemioliopterus) are found in the Amazon, Orinoco, and Essequibo river basins of South America, which span across Ecuador, Venezuela, Brazil, Colombia, and Peru. These bottom-dwelling fish are common in the wild and thrive in large rivers and streams.
Redtail catfish are the sole surviving species of the genus Phractocephalus.
Adult Size & Lifespan
In the wild, fully-grown redtail catfish reach up to six feet in length and can weigh up to 180 pounds. Due to their enormous size, redtail catfish are often treated as game fish by anglers. Captive redtail catfish are three to four feet long on average.
Juvenile redtail catfish are small — only a few inches — but grow rapidly. There are no known size differences between male and female fish. Redtail catfish have an average lifespan of 15 years in captivity but live longer in the wild.
Redtail catfish are widely available in the US. Unfortunately, redtail catfish are often sold as juveniles to fishkeepers unaware of their rapid growth and adult size.
Many store-bought redtail catfish are given up and rehomed into public aquariums once they become too big to handle. Avoid buying redtail catfish if you lack experience and can’t accommodate the fish’s adult size.
A juvenile redtail catfish costs between $20 and $40, while adults can cost up to $200. Redtail catfish can be bought online from Aqua-Imports or Arizona Aquatic Gardens.
Appearance & Behavior
The redtail catfish gets its name from its vibrant red tail. Redtail catfish are territorial and are natural predators.
Colors, Patterns, Fins, and Sex Difference
The redtail catfish has a grayish-brown, spotted body with a red tail. The dorsal and caudal fins are orange in coloration, and the fish has long barbels (whiskers) on its mouth. A pale yellow band spans across its body.
The redtail catfish is slender and has a flat underbelly. They aren’t sexually dimorphic, meaning it’s impossible to tell females and males apart. When stressed, redtail catfish lose their vivid tail coloration.
Redtail catfish are bottom-dwelling fish that prefer to live alone. These fish won’t hesitate to attack smaller species, and they often exhibit territorial aggression if there are too many fish in the aquarium. Juvenile redtail catfish are shy and require lots of hiding spots to feel at ease.
Redtail catfish are slow swimmers and spend most of their time in the bottom regions of the tank. They are rarely active during the day.
Despite their voracious appetites and predatory nature, these fish are peaceful when kept with the right tank mates and in the appropriate tank conditions.
Redtail Catfish Care & Tank Requirements
Redtail catfish are difficult to care for because of their large size and semi-aggressive nature. These fish require a 1,500-gallon aquarium or larger to thrive.
Replicating their natural habitat helps the fish feel at home in captivity. Feed them a varied diet and ensure food sinks to the bottom of the tank.
Habitat and Tank Requirements
Redtail catfish are found in a range of environments in the wild, including lakes, streams, and rivers. These fish do best in warm, moderately soft water.
Keep redtail catfish in the following tank conditions:
|Water type:||Freshwater, with weekly changes (30% of water volume) |
Redtail catfish are messy eaters and often displace substrate, so frequent water changes are essential
|Tank size:||Minimum 1,500-gallon aquarium for mature fish. Juveniles should be moved to larger tanks as they grow|
|Water temperature:||70–79°F (21–26°C)|
|Substrate:||None. Redtail catfish may try to eat substrate|
|Tank setup:||Add a few decorations to provide hiding spots |
Decorations should be sturdy and durable so they can’t be displaced or eaten. Avoid driftwood and small rocks. Tie any loose decorations down.
|Water hardness:||Moderately soft water, between 3–12 dGH|
|Filter and heater:||Sump-style filter and external heating system. An external system is necessary to prevent the fish from damaging or eating it. Check daily for blockages |
Avoid filters that generate a powerful current because redtail catfish are accustomed to slow-flowing water
|Pump:||Yes, to provide water movement for gas exchange|
|Lighting:||Dim lighting, as the fish become stressed if exposed to harsh, direct lighting. If a dimly-lit environment isn’t available, create shaded areas with caves for the redtail catfish to retreat to|
Monitor water parameters and test nitrate and ammonia levels regularly. Redtail catfish often surface to gulp air in poor water conditions.
Redtail catfish are hardy, but poor tank conditions can make these fish susceptible to common freshwater ailments such as fin rot, flukes, and nitrite poisoning.
Ensuring water conditions are optimal prevents illness. Avoid exposing redtail catfish to stressful situations, and quarantine new decorations or fish for two weeks before adding them into the aquarium.
Fin rot is a bacterial or fungal infection that causes the fins to decay and appear tattered and dull. Other symptoms include sluggish behavior, fin inflammation, and appetite loss. Fish develop white edging on their fins if the fin rot is caused by a fungal infection.
Fin rot is treatable with antibiotics or antifungal medication, though redtail catfish are sensitive to medication. To treat, use antibiotics, increase water temperature slowly to 79°F, and ensure the pH level is correct.
Skin and Gill Flukes
Flukes are small, worm-like parasites that live in the skin or gills. They reduce the fish’s ability to take in oxygen and cause lesions that can bring about secondary infections.
Symptoms of flukes include flashing behavior, breathing difficulties, lethargy, and appetite loss. Flashing is when the redtail catfish rubs its sides against the substrate, tank walls, or decorations.
Treat flukes with medication and keep the water clean. Avoid copper and potassium permanganate medications because redtail catfish are scaleless and sensitive to these particular treatments.
Nitrite poisoning happens when redtail catfish are exposed to high nitrite levels over a long period of time. A sudden spike or drop in nitrite levels can kill redtail catfish within days. Symptoms of nitrite poisoning include infected barbels, sluggish swimming behavior, and rapid gill movement.
Treat nitrite poisoning by reducing feedings and increasing aeration. Carry out regular water changes and use water test kits to monitor nitrate and ammonia levels daily.
Redtail catfish shouldn’t be housed together because these fish are highly territorial with one another. You can keep them with other species, but tank mates must be similar in size. Redtail catfish are predatory and eat smaller fish.
Suitable tank mates for the redtail catfish include:
- Large stingrays
- Large datnoids
- Iridescent sharks
Avoid invertebrates like shrimps and crabs because redtail catfish eat anything that can fit in their mouths. Keeping redtail catfish with other tank mates requires an immensely large aquarium — larger than most hobbyists can realistically provide and afford.
Diet and Feeding
Redtail catfish are omnivores that require a protein-rich diet. In the wild, redtail catfish eat anything they can find, including crustaceans, small fish, insects, and fruit.
Ideal foods for the redtail catfish include sinking pellets and both live and frozen foods like shrimp, crayfish, small fish, and worms.
As a general rule, adults should be fed on a weekly basis. However, reduce or increase feeding frequency based on the fish’s activity level. These fish become sluggish after a meal, and should only be fed when they become active again.
Avoid overfeeding redtail catfish, as they’re prone to overeating and struggle to digest food. They shouldn’t be fed the meat of mammals because they aren’t able to metabolize this food properly. Juveniles should be fed high-quality flake food or pellets, every other day.
Redtail catfish are egg layers. Breeding redtail catfish in a home aquarium isn’t possible due to the fish’s large size and aggressiveness toward its own kind.
Most redtail catfish in the commercial trade are bred in fisheries with the use of hormones.
Should You Get a Redtail Catfish for Your Aquarium?
Redtail catfish are hardy and attractive, but the fish’s large size and predatory nature make it suitable only for experienced fishkeepers.
You should consider a redtail catfish if you can accommodate and afford a 1,500-gallon aquarium or pond setup, and will be able to care for this fish throughout its long, 15-year lifespan.
Don’t get a redtail catfish — even a juvenile — if you can’t accommodate its adult size, expect to breed the fish, or lack experience.
Under the care of the right fishkeeper, redtail catfish make captivating additions to a freshwater aquarium.
I plan on getting one this Monday I have a tiger shovel nose catfish already I’m building a pond for them both my pond is gonna be 8×8 5 feet deep. I’m very excited and can’t wait to own the little guy
Sounds great Ryan! Keep us updated 🙂
Thank you for this updated, I wanted to find out about some diseases of this fish and how to treat it, because my fish died 2 days ago, he didnt eat nothing and tired
I’ve got a redtail now 18 inches long, getting a bigger tab nk, 150 gal. Where can I sell it, know it will have to go sooner than later. Don’t want him eatting my other latge fish = blue cat, needle nose gar
thanks a lot.
this stuff is easy to read and understand.
although it made me not to buy a red tail catfish because I do not have a big enough tank… 🙁
I saw a beautiful 10″ retail in a Petland in the West Village NYC. It is in a tiny tank way too small -maybe 20 inches. It was heartbreaking to see. The woman at the counter told me a customer abandoned it in the store in a bucket and they were required to keep it.
I am not a fish person per se but I would would love to help this beautiful fish be in a better situation. Any ideas?
Unfortunately this happens all to often. Are you able to provide it with the tank size and all the conditions we have covered above?
We have a huge Koi pond out back and I recently purchased 3 of the redtail cats to put in the KOi pong. They are all very small at this point, but 2 of the 3 have disappeared. None of the KOI are missing, so I don’t think it was a predator, but I can’t find a dead fish around the sides either. Any clue what might have happened to them?
What a mystery! No suggestions unfortunately, do let us know if you ever find out. Be careful are the other RTC grows – it may eat your koi!
Ive seen Koi in a tank eat worms and eat a dead comet feeder fish. The RTC’s could have died from water conditions or something along those lines and then the Koi cleaned up. I know this was posted a year ago but just in case someone googles the questions and finds the answer. Thanks!
I recently brought a pair of Redtail Catfish about 2inches in size. One of my catfish died 2 days later. I fed them tuna the night before one died. The other one is doing good and looks healthy. But he is alone in the tank now. I have setup everything in the tank for them heater filter and hiding place. Heater is set at 26 degree celcius. But I don’t know what happened. I just found him at the bottom of my tank dead. Can you help me with what happened to my catfish and should I buy another catfish for my other one or will he do good all alone. Now he is in a 100 litre tank. I’ve ordered for a 1500 litre tank. Will get it next week.
It’s difficult to know the exact cause of death of your RTC. A 1500 litre tank is still nowhere near big enough for even one RTC. We recommend a minimum of 1000 gallons, which is around 4500 litre tank.
Thankyou Robert. Will get a 4500 litre tank. But will he be bored staying all alone in that big tank.
I plan on getting 2 RTC and i was wondering if a 20 x 6 1/2 x 3 1/2 foot pond was big enough for them. Also wondering how big of a red tail a 50 gallon tank could hold as a growing tank as i plan to get babies and don’t have room for a bigger tank.
These guys grow extremely fast, there is no way a 50 gallon tank will last them more than a couple of months.
It’s important you get them into their final pond or tank ASAP so you don’t stunt their growth.
Understood, but I am just using the 50 gal tank to grow them out large enough to be put into the pond which will be 20x8x5 feet. Will that be large enough to hold one for its’ entire lifespan?
This size should be OK, if you can stretch any bigger I would suggest doing that.
Would koi fish be a good pond company for a redtail cat I’m wanting to get both but I want to make sure an what size the pond should be any tips would be a huge thanks
It really depends on their size. As a long term solution, I would say no. I have known RTC’s to eat Koi. Thanks, Robert
Hello folks. I’m thinking about putting a lake on my property in southern Spain. I have some experience with red tails as I’ve caught them in asia. My question is with regard to water temperature and if they will be able to survive in Europe in an outdoor lake. It’s not so cold like most of Europe but winter temperatures can fall to 16-18C in the daytime and 10-12C overnight.
I see these fish a primal survivor types having handled many of them. In fact I’ve often joked you could fire a bullet into them and they would survive they are that tough.
The only question mark I have really is the water temperature thing? Can anyone help me out?
If RICS are a no go I am thinking about some goonch of Indian origin. I want to grow a few monsters so I’d also be happy to heat if anyone has any other ideas of what I could happily stock into the lake in such a climate? Wels cats I am not a fan of by the way which is the indigenous variety here in Europe.
Grateful for any and all info
This sounds like a great idea, I’ll leave your question here in hope that someone has a similar experience to share tips with you. Thanks, Robert
Can you have them in an outdoor pond without a heater and store them in an indoor tank during the winter? In southern Cali btw.
As long as the temperatures that they stay in remain in between 68-79oF and stay as consistent as possible. Thanks, Robert
Does anyone know what age my Redtail will get its Redtail
Hi Tyler, the color should develop within the first few weeks. If it’s not red it could be a possible indication of stress. What size tank are you keeping your RTC in? Thanks, Robert
I hve recently bought two baby Rtc’s and looking forward to give them healthy habitat in pond which I have in backyard once they grow. Presently kept them with silver Arowana. Nice article, helped me to understand RTC in much better way.
Good luck raising your RTC’s, thanks for the message Mack. Robert
I need help…I ordered a Zebra Plecostomus from an online store for $4.99. Stays smaller and easy to care for. I get this nice package in the mail, perfectly packaged and transported very carefully and open it up and wouldn’t you know….they sent me a Red Tail Catfish by mistake and they refuse to take it back as I made the mistake of putting it in my tank (I wasnt going to leave him in a bag inside a box and take him to the post office for Christ’s sake). I have a 30 gallon tank and cannot find anywhere suitable for this little guy to go…I’ve even started calling aquariums but they’re also picky because he is in a private residence tank. How long can a tiny 30 gallon tank sustain him while I search for his home? I have a 320 gallon tank that I haven’t had set up for almost 5 years, but even that I don’t imagine would last more than a year, two tops. Any advice is greatly appreciated.
Hi Kris, I’m sorry to hear about this. If possible I would get him into the 320 gallon ASAP, he’ll grow out of a 30 gallon within weeks. I really hope you manage to find a home for him. Are there any specialist fish shops near you? I’ve found that private ones are more likely to take on these fish than chain stores. Let me know how you get on. Thanks, Robert
Can someone tell me if my fish got some disease. We got two baby RTCs and today we noticed clear bubbles on their whiskers. What could this be? Both of them have it. Please help!
Hi Alex, do they have any other symptoms? Is it possible they are just air bubbles? Thanks, Robert
Although I very much agree with the comment of having a large enough system to house an adult instead of buying these cute guys small and as they grow get a bigger setup as this unfortunately rarely happens. And these guys grow fast, faster then your imagining if you’ve never had one. But I’m here as a rarity because I committed. As my first “monster” fish, 1st monster tanks, 1st DIY tank sump filter builds, I had to pick these guys as they are stunning and very personable like water puppies. Knowing I was going to build a huge setup, a dealer friend of mine got an order in and had to show me and I fell into it. I had to have one now..lol.. and ground had not broke on the pond build. So began the ever so quick tank upgrades: 20gal(pointless), 40gal, 55gal short, 75gal, 110gal and now to a temporary 660gal pond. Now to give an idea of the speed in which the upgrades took place, at 2.5 inches in a 20gal to now a 8.5 foot × 5.3 foot × 2 foot deep 660gal above ground pond has taken place in 6 months with a 20+ inch Redtail and a 14inch RTC×TSN hybrid. With all the collected free or cheap materials i could find and most items bought at msrp were not originally marketed for fish keeping but do the job as well or better and assembled filtration and temperature control systems and it still cost me a few hundred(trying to keep costs down to put into the final habitat) just to put this 660gal together and it’s only temporary until the 2000gal is finished. And trust me a few hundred on a temp 660gal is nothing compared to a 2000gal setup even designing and building it myself it will be more than $1000usd just for materials. Now I say this as a warning but in a good way, just be ready. I committed and have done what it takes to keep up that commitment but it is and will continue to be a whole heck of a lot of work and for now it’s all being done for just 2 cat’s. And even if it where 1 cat the same amount of time, energy and money would have gone into the care. And yes money: upkeep(filter),energy(multiple pumps(water/air),water movers, heating/cooling with thermostat controller, water, oh and food. I dont think enough people remember to think about the food bill with any type of pet, but especially “monster” fish like these. If you have ever had a medium to large dog on a straight one brand dry diet food think of that and imagine 1 redtail costs more to feed in its first year (as I can only speak to the first year) then my full grown Siberian Husky during the same time span. So as a take away, yes wait until you have the proper size setup before even buying a little RTC it will save you a ton of work though I would still say it was/is worth it but unnecessary, plus some like mine do not like a constant and significant change to their environment causing stress in my case food strikes. I’m self admitting this as my number one reason not to go the route of increasing your tank size as they grow even if you can keep up as a rare case with the required space requirements, as it can cause unnecessary stress to the fish and you . 2 please dont look at the price of buying a fish as your biggest expense with these guys its many times over their costs to care for and feed them every month. Water alone, find your water bill and note your cost, 100gals every 2 weeks to top off from evaporation and 50% about 300 gallons every 2 weeks for a water change. That’s 800 gallons a month and this is after 6 months. Their final enclosure I’m estimating approximately 2200 gallons a month. On that note take up gardening as this amount of natural liquid fertilizer and water should not be wasted. And one more note keeping a large pond inside if you have the space is an excellent way to save on heating and cooling however if it shares the air of your living space it will make it quite humid and typically the temps at which they are kept are warmer than most peoples typical inside settings and that large body of water will warm the surrounding air rather efficiently. So you will need to have a separate indoor space from your living space or go for an outdoor pond but keep it shaded and remember it is now a greater cost for heating or cooling, especially depending on where you live, and must be done year round as this is not a koi pond. They need mid 70sF to low 80sF. I dont believe any geographical location sees those temps night and day for more than a few weeks I would imagine. Personally in the Sonarn Desert our short winters can be as low as high 30sF in the day to mid 20sF at night for a few weeks out of the year and as high as 115F during the day and 90sF at night. So in my case both heating and cooling systems have to be utilized. But dont let this scare you. It can be done and at a reasonable price just do ample research and do as much as you can yourself and you will have a gorgeous pet for years to come( oh yeah this is a longer commitment then your cat or dog) and well worth it in my opinion as you take pride in providing this animal with what it needs to live a healthy life where many have failed for one reason or another, they are a wonderful unique conversation subject and mine anyways is really just my big water puppy. They may seem stand offish or shy but that’s only because they prefer to be more nocturnal. They are very smart and they do learn and remember. If you are getting one you will not be disappointed with your experience interacting with your RTC. Sorry that was lengthy I hope sharing my experience might help at least one person in some way.
Hi Dallas, thanks so much for sharing your experience! Robert
I bought one at the local pet store it was very small I’ve had it a month it’s more than tripled its size I was told it would only grow to be 7 or 8 inches long it’s already around 5 I have a decent good sized tank he has plenty of room as of now and t grow but the pet store should have done there homework on this one this article helps out a lot
I bought a RTC and he was around four inches, I had him for only 3 – 4 weeks and it is already 5-6 inches. I am petting him in a 20 gallon tanks with 3 more oscar fish. Do you think the tank is overcrowded? I am thinking about swapping the 20 gallon tank fish to a 50 gallon tank but my 50 gallon tank has 10 african cichlids in there. So if I swap them, the 20 gallon tank with the cichlids would be over crowded, What should I do? I have a Koi pond ready for the red tail catfish but it is too small for the pond right now, I am scared it will get eaten up by the Koi because the koi are around 1 feet to 1.5 feet long!
I have one with my business partners shovel nose and a pacu the rtc is about 28inches i think, the shovel nose is 24 or 25 inches and the pacu is pushinv 20 easy
Can I keep red tail in a pond with bass I think the pond is 1/2 an acre
I need help figuring this out please
Can I put a Rtc with bass in 1/2 an acre pond and the Rtc won’t eat the baby bass