Red-tailed black shark Care Guide: Diet, Tank Mates, Diseases, Breeding & More

Updated: December 17, 2022

The red-tailed black shark is a freshwater fish that is popular in the aquarium trade. They are easily recognizable by their black body with a bright red tail.

This species can grow to be about a foot long, so they need a fairly large tank. They are also a bit on the aggressive side, so they need to be kept with other fish that can hold their own.

This guide will teach you everything you need to know about red-tailed black shark care. You’ll learn about their diet, size, lifespan, and more!

Species overview

The red-tailed black shark (Epalzeorhynchos bicolor) is a freshwater fish that is native to Thailand.

They are found in slow-moving rivers and streams with a sandy bottom and plenty of hiding places.

This fish gets its name from its black body with a bright red tail. It is a popular aquarium fish but can be aggressive toward other fish.

The red-tailed black shark is a carnivore and in the wild, it feeds on insects, crustaceans, and small fish. In the aquarium, it should be fed a diet of live or frozen foods.


Red-tailed black shark

As the name suggests, the most defining characteristic of this fish is their long, black tail. The tail itself is quite thin and tapers towards the end.

The body of the Red-tailed Black Shark is a deep, dark gray. The belly area is a bit lighter in color, but not by much. You’ll also find a black stripe that runs along their sides (from snout to caudal fin).

This stripe is one of the most defining features of this species and is what sets them apart from other black shark varieties.

The fins on the Red-tailed Black Shark are relatively small compared to the rest of their body. The dorsal fin is slightly taller than the anal fin and both of these fins have a black leading edge.

Their pectoral fins are also black along the leading edge with a white trailing edge. The caudal fin is forked and symmetrical.

You’ll also find that the Red-tailed Black Shark has barbels (or “whiskers”) on their snout that they use to help them find food in dark waters.


The average lifespan of a red-tailed black shark is around 5 to 8 years. However, there have been reports of these fish living up to 10 years in captivity.

As with any other fish, the lifespan of a red-tailed black shark can be impacted by a number of factors. Poor water quality, for example, can shorten their lifespan significantly.

Stress is also a big factor. If these fish are constantly being harassed by tank mates or if they’re not getting enough to eat, their lifespan will be shortened.


The average size of a red-tailed black shark is about 12 inches long. However, they can grow to be up to 18 inches long in some cases.

As you can see, the size of your fish will play a big role in how you set up their tank. Make sure you take this into consideration when planning your aquarium!


Tank Size

The minimum tank size for a red-tailed black shark is 50 gallons. If you want to keep more than one fish, you should add at least 30 gallons for each additional fish.

These fish are active swimmers and need plenty of space to move around. A larger tank will also give you more room to add other fish as tank mates.

Water Parameters

As with any fish, you need to take care when adding a new fish to your aquarium.

Adding a red-tailed black shark to a community aquarium can be a bit tricky. They’re not the most social fish and can be a bit aggressive, especially when they’re younger.

The best way to introduce them to a new aquarium is by adding them last. That way, they can’t claim any territory and will be less likely to become aggressive.

You also need to make sure the aquarium is large enough. These fish grow quickly and can reach up to 18 inches in length. A 50-gallon aquarium is the minimum size you should consider.

Finally, you need to make sure the water parameters are ideal. Red-tailed black sharks are native to Thailand and prefer warm, slightly acidic water.

  • Water temperature: 76 to 82 degrees Fahrenheit
  • pH levels: 6.5 to 7.5
  • Water hardness: 5 to 15 dGH
  • Alkalinity Levels: 4-8 dKH

What To Put In Their Tank

These fish come from fast-moving rivers so they’re used to a substrate that provides some resistance. This is why we recommend using gravel or sand in their tank.

As for the other decorations, you have a few options. These fish love to hide so including some driftwood, rocks, or caves is a good idea.

Just be careful with the caves. These fish are known to get territorial with their hiding spots. If you have more than one shark in the same tank, make sure there are enough caves for everyone.

Plants are a bit of a touchy subject with red-tailed black sharks. In the wild, these fish come from habitats with very few plants. This is why a lot of aquarists don’t bother adding any vegetation to their tank.

That being said, if you want to add plants we recommend going with something that can handle a little abuse. Java Fern and Hornwort are two of the best options.

Common Diseases

There are a few diseases that you need to look out for with your red-tailed black shark. While they are a rather hardy fish, they are still susceptible to the usual freshwater culprits.

The most common disease that affects this species is ich. This is a parasitic infection that will show itself as white spots on the body of your fish. If left untreated, it can be fatal.

The best way to treat ich is to raise the temperature of the water in your tank. This will speed up the life cycle of the parasite, allowing you to more easily remove it with medication.

Aside from ich, another common disease that affects red-tailed black sharks is hole-in-the-head disease. This is caused by poor water quality and the presence of activated carbon in your tank.

It will present itself as one or two pits/holes in the skin of your fish’s head. While it’s almost always curable, it will usually leave some scarring on your fish.

To prevent these diseases, it’s important to maintain the quality of the water in your tank. A tank with clean and stable water conditions will always lead to healthier fish who are more resistant to disease.

Behavior & Temperament

The red-tailed black shark is a semi-aggressive fish that is known for being territorial. This fish is not recommended for beginners. They are also not recommended for community tanks because they may attack smaller fish.

This fish is mostly active at night, but they can be seen swimming during the day. During the day, they will mostly stay near the bottom of the tank.

The red-tailed black shark is a carnivore and will eat smaller fish, so it is important to only put fish in the tank that are too large to be eaten.

This fish is also known to be fin nippers, so it is important to have a tank that is big enough for them to swim around and not get bored.

Tank Mates

The list of potential tank mates for a red-tailed black shark is pretty short.

These fish are semi-aggressive and will harass other fish in the tank. They’re also known to be nippy, so any fish with long fins is likely to get shredded.

To make matters worse, they’re also known to eat smaller fish. This is one of the reasons why they’re not recommended for community tanks.

The only fish that can really hold their own against a red-tailed black shark are other sharks. This includes species like the rainbow shark, bala shark, and iridescent shark.

These are all semi-aggressive fish that can handle the red-tailed black shark’s aggression. Of course, you’ll need a pretty big tank to house all of these fish!


Breeding these sharks is pretty difficult and not much is known about the process. It is thought that they reach maturity at around 2 years of age.

Males and females are similar in size, with the males being slightly larger. The best way to tell them apart is by looking at the fins. Males have longer and sharper dorsal and anal fins.

To breed these fish, you’ll need to set up a breeding tank. It should be at least 50 gallons and have a sandy bottom. Make sure the water is well-oxygenated and has a temperature between 75 and 80 degrees Fahrenheit.

You’ll also need to add some plants and hiding places. These fish like to have a lot of places to hide.

When everything is ready, add one male and two females to the tank. The male will chase the females around until he’s ready to mate.

Mating usually takes place in the morning. The male will nudge the female’s belly until she releases her eggs. He will then fertilize them.

After that, the female will swim away and the male will stay to guard the eggs. He will fan them with his fins to keep them oxygenated.

The eggs will hatch in about a week. Once they hatch, you can remove the adults from the tank. The fry will feed on microscopic organisms in the water. You can supplement their diet with baby brine shrimp.


The Red-tailed Black Shark is a beautiful and unique fish that is sure to stand out in your aquarium. They are relatively easy to care for but do require a bit of extra attention when it comes to feeding and water quality.

Overall, we think they make a great addition to any freshwater tank and would recommend them to anyone looking for a new and exciting addition to their aquarium!