Red-tailed shark are wonderful, active fish who make excellent an excellent addition to any suitable aquarium.
In this guide, I’ll teach you how to provide red-tailed shark with the right environment and tank mates so you can successfully care for them.
Red-Tailed Shark (Epalzeorhynchos bicolor) Quick Stats
- Care Level: medium
- Min. Tank Size: 40 gallon (151 liter)
- Temperature: 75°-79°F (24°-26°C)
- Diet: omnivore
- Temperament: semi-aggressive/aggressive
- Lifespan: 5-10 years
- Size: 6 inches (15 centimeters)
- Family: Cyprinidae
- How many can be kept together: only one
- Scientific Name: Epalzeorhynchos bicolor
- Common Name: Red Tail Shark, Red-Tailed Shark, Redtail Shark
Red-Tailed Shark Species Profile
Red-tailed sharks are native to Thailand, where, unfortunately, they are critically endangered.
When they were abundant in the wild, they were often found in clear, fast-running waters. They are also known to migrate into flooded forest floors during the rainy season.
They are a solitary species that spends its time scouring the substrate for biofilm, algae, crustaceans, worms and insect larvae.
Appearance
Red-tailed sharks are striking fish. They have coal black bodies with, you guessed it, bright red tails.
They’re very slim-bodied fish with high, triangular dorsal and anal fins. Their pectoral fins are almost completely transparent and their large, rounded pelvic fins are closer to their tails than most fish.
This makes them highly maneuverable; they can turn on a dime and give you five cents change.
They have the downturned mouth typical of carps and other bottom feeders, and short, rear-facing barbels at the corners of their mouths.
These guys are sexually monomorphic, meaning that both male and female fish share the same form. There is no way to look at the fish and determine whether they are male or female.
And just to get something straight, they are not an actual shark, not even close. This species is classified as a part of Cyprinidae, the same family as carp, koi and Goldfish.
Totally, utterly, not even anywhere near being an actual shark.
Red-tailed sharks get their name because their silhouette is very similar to slim-bodied sharks, like blue sharks or blacktip reef sharks.
I can say, the way their body and fins move will definitely remind you of fast-moving sharks. Their swimming looks almost hypnotic, it’s super cool.
But, this is where the similarities to real sharks ends.
In the Aquarium
I can’t emphasize this enough, these are generally not good community fish. I consider them to be semi-aggressive to aggressive.
They will relentlessly chase other fish. Timid species will not do well with this fish in the tank.
I once observed a little 3 inch (7.5 centimeter) long juvenile red-tailed shark chase and bully a Texas cichlid five times its size. I couldn’t believe it, but I saw it again and again.
By the time that fish reached 6 inches, it was the boss of the tank and would chase off some seriously mean fish whenever it felt so inclined. Craziest thing I’ve ever seen.
Also, you cannot have more than one of these fish in your tank. Some people get away with it for a short time while the fish are juveniles, but long term, the fish will harass each other continually until one or both of them are dead.
How to Set Up a Red-Tailed Shark Tank
Tank Size
I would recommend at least a 40 gallon (151 liter) aquarium for these fish. If they feel too crowded, they will be even more aggressive with tank mates.
A 40 gallon will give this fish ample room to stake out a territory.
Filtration
Filters on aquariums are so important. Without them, healthy fish tanks wouldn’t be possible.
Special beneficial bacteria live inside the biomedia of the filter. These bacteria live off the toxic substances, like ammonia and nitrite, put off by fish urine and feces as it breaks.
The bacteria eats the toxic ammonia and nitrite and turns it into nitrate, a substance that isn’t harmful at low levels.
This is known as the Aquarium Nitrogen Cycle.
Without the beneficial bacteria that carry out the cycle, waste products would build up in the aquarium, making the water toxic for fish.
As for this particular species, I’ve kept red-tailed sharks in several different tanks utilizing a variety of filters. These fish do great with high flow filtration, like canister filters or powerful hang-on-the-back filters.
And I’ve also seen them thrive with low flow filtration, like sponge filters. As long as the water is clean and the parameters are healthy and stable, a red-tailed shark can handle it.
Water Parameters
- Temperature: 72°-79°F (22°-26°C)
- Ammonia/Nitrite: 0
- Nitrate: <30 ppm
- pH: 6.0-8.0
- GH: 3-15 dGH
- KH: 3-10 dKH
Heater
Red-tailed sharks come from a tropical region and will therefore need a heated tank.
I highly recommend a heater with a guard on it. Sometimes these guys try to get too close and can burn themselves.
My favorite heaters on the market are the Fluval E-series. I have three of these that I’ve used for more than a year now. I love them and they’re all I’m going to be buying in the future.
For our in-depth article comparing popular heaters on the market click here.
Substrate
I would recommend sand or smooth gravel for this species. They don’t dig a lot, but they will nose around on the surface of the substrate looking for bits of food.
A sharp or rough substrate could scratch up their noses and mouths, leaving them vulnerable to infection.
Lighting
This species really doesn’t have a preference when it comes to lighting. Just go with whatever kind of light you want for the tank.
Plants and Decor
If you’re wanting to set up a bare, open tank, this is not the right species for that kind of setup.
Red-tailed sharks like to set up a little territory, usually centered around their favorite hiding spot.
It’s best to provide them with lots of hiding places, especially some caves. Add lots of decor, rocks, plants and driftwood to create a complex environment for them.
This species will often hide for stretches of time during the day so they’ll need a hidey hole that they can fit in comfortably. Remember, the adult fish will be about 6 inches (15 centimeters) long, so they will need a space at least that big.
They appreciate things like driftwood and rocks that they can hang around, especially when they’re small.
Also, since these guys often chase other fish, having lots of rocks, driftwood and plants breaks up their line of sight so other fish can escape their wrath.
This species does not tear up live plants. In fact, they lightly graze the surface of leaves as they munch on algae and biofilm. A red-tailed shark won’t keep your plants completely algae free, but they will help a bit.
Red-Tailed Shark Diet
These guys are not picky eaters. They’ll munch on just about any kind of food that drifts down to the bottom.
I especially like to give them sinking wafers. I know that a sinking food will get past all the hungry top dwelling fish and wafers are big enough to not get stuck down in the gravel where the red-tailed shark can’t get it.
Just check the ingredients because a lot of “algae wafers” contain a bunch of crap fillers.
Omega One Veggie Rounds are a very good choice. I’ve always gotten excellent growth using them as the staple diet for my red-tailed and rainbow sharks.
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Red-Tailed Shark Breeding
It’s not possible to breed red-tailed sharks in a home aquarium setting.
You can’t keep them together, they’ll tear each other apart. And you can’t tell who’s male and who’s female.
And they won’t spawn unless hormone treatments are added to the water.
So, no little baby sharks in your tank.
Red-Tailed Shark Tank Mates
OK this can be hard to answer.
Red-tailed sharks can be quite aggressive. They will incessantly chase any tank mate that wanders into their territory, even fish four or five times their size.
They don’t necessarily hurt the fish they chase, their mouths aren’t really built for biting, but tank mates can get really, really stressed by the harassment.
It’s best to place red-tailed sharks with other semi-aggressive, or even flat-out aggressive fish.
My number one recommendation is tiger barbs. I know their jaunty little stripes make them look adorable, but don’t be fooled. Tiger barbs are tiny little velociraptors that will gang up and harass other fish to death, literally.
But the red-tailed shark is tough enough to handle the barbs and vice versa.
I’ve also had great success with keeping both rainbow and red-tailed sharks with African cichlids (I used to have a tank full of mbuna), as long as there is lots of hardscape and decor that the shark can use as cover. You also have to make sure that the cichlids aren’t so big that they can easily swallow the shark.
Red-tailed sharks have such salty personalities that I’ve seen them chase fish five or six times their size. A tank full of cichlids will not intimidate them.
I do not recommend putting them in a tank with timid bottom feeders, like corydoras catfish. The two species will come into conflict over feeding and territory along the bottom. The red-tailed shark can be relentless against shy fish.
There are many reports that red-tailed sharks get along well with clown loaches, even schooling with them. However, in order to keep these two species together, you’d need a tank in excess of 150 gallons (568 liters).
Is a Red-Tailed Shark Right for You?
This species is wonderful and really fun to watch as they go about their day. But, they are not the right fit for every tank.
Red-tailed sharks can be really bad about harassing tank mates, sometimes even to the point of stressing other fish to death.
You do not want to put this species in with a bunch of super peaceful, delicate fish. It won’t go well.
However, this species is great for adding some variety to a tank with other semi-aggressive and aggressive fish.
These little terrors can handle themselves just fine, even with notoriously difficult roommates like mbuna cichlids.
Other than the issues with aggression, this species is hardy, undemanding and long-lived, great for even beginners. And their spunk and bursts of energy are so entertaining to watch.
I hope you find this article helpful.
I wish you and your fish the very best!
