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Red Tail Shark – An Eye-Catching Freshwater Fish Guide

Red tail sharks are striking fish that remain relatively small but are very active in the aquarium, making them an excellent choice for many home aquariums.

While they can be aggressive in an aquarium environment, when provided with the right conditions, they can get along with a number of different kinds of fish.

Red Tail Shark

Here’s what you need to know about caring for a Red Tail Shark and how to decide whether this is the right fish for your aquarium. 

Red Shark Quick Information

Temperament Semi-aggressive
Lifespan 5 – 6 years
Size Up to 6 in
Water flow Fast
Aquarium size 30 gallons for juveniles and 55 gallons or more for adults 
Aquarium decor Plenty of plants and driftwood to reduce territorial behavior 
Temperature  Between 72°F and 79°F
PH: 6.8-7.5.
Water hardness 5-15 dh.
Lighting Medium to low light or sufficient live plants to obstruct light
Compatible tankmates Tetras, gouramis, barbs, danios, angelfish, bala sharks 
Available captive-bred? Yes
Family group  Cyprinidae 
Close relatives Rainbow shark
Feeding Difficulty Easy
Schooling Fish? No, Red Tail Sharks shouldn’t be housed with other Red Tail Sharks
Diet High-quality fish flakes or pellets as well as brine shrimp, bloodworms, peas, zucchini, cucumber, and fruit

What is a Red Tail Shark?

The Red Tail Shark (Epalzeorhynchos Bicolor), also known as a Red Fin Shark,  is a very popular fish in the aquarium hobby. They are striking, with their pitch-black bodies and sharply defined red tail. They are native to Thailand, although they are nearly extinct there, primarily due to changes in their natural habitat.

Despite the name, Red Tail Sharks are not actually sharks. However, they have a distinct dorsal fin and a torpedo-shaped body that makes them resemble a marine shark, hence the name. In fact, they are a type of carp belonging to the Cyprinidae family. 

Red Tail Sharks are fairly easy to keep in an aquarium, provided they have sufficient room and compatible tankmates and conditions. They are not picky eaters and are not as particular about water conditions as some other fish.

Rainbow Shark vs Red Tail Shark 

While Rainbow Sharks and Red Tail Sharks look quite similar, they are actually different species. They have distinctly different physical characteristics, particularly the fin color, and slightly different behavior.

Rainbow Shark vs Red Tail Shark 

The terms Rainbow Shark and Red Tail Shark are sometimes used interchangeably. However, these are two different species, even though they are close cousins. In the Rainbow Shark, the pectoral, anal, and dorsal fins are all red, whereas in the Red Tail Shark these fins are black.

Only the tail is red in the Red Fin Shark. Some individuals also have a white tip on their dorsal fin.

Rainbow and Red Tail Sharks don’t just differ in their appearance. They also have different personalities. Rainbow Sharks tend to be more reclusive than the Red Tail Shark, and they need plenty of places to hide and escape from the flow and activity of the aquarium. 

Both Rainbow Sharks and Red Fin Sharks are semi-aggressive and may chase slower-moving fish and bottom feeders. 

Red Tail Shark Behavior

Red Tail Sharks tend to be nocturnal, but keeping the aquarium somewhat dimly-lit or providing shadowed areas using decorations will enable you to see them during the day.

During the day, they often like to hide in dark caves and dart out to snag a meal or chase another fish out of their territory. Red Tail Sharks tend to swim near the bottom of the tank, where they graze on algae and feed on debris that falls down to the bottom. 

Many hobbyists find that their Red Fin Sharks are very interesting to observe. These fish tend to be more intelligent than some other fish in the home aquarium. You may be less likely to see behavior like rubbing up on the glass in Red Tail Sharks than in other species, which can make them more pleasant to observe.

Because they interact with their environment in interesting ways by hiding in caves and swimming among plants, they make fascinating aquarium residents.

Will Red Tail Sharks Kill Other Fish? 

As juveniles, Red Tail sharks tend to be quite timid. They are unlikely to become aggressive with other fish and would only kill fish that are small enough for them to easily eat. Red Tail Shark size as a juvenile is only a couple of inches, so most aquarium fish won’t be considered a food source for it. 

However, as they get older, Red Tail Sharks tend to become increasingly territorial. 

They are intolerant of most other sharks, such as other Red Tail Sharks or Rainbow Sharks, although they do tolerate Bala sharks.

It may be possible that in an extremely large aquarium (larger than 200 gallons) with plenty of hiding places, two Red Fin Sharks could co-exist. In this case, both sharks will stake out one side of the aquarium and defend it from each other. This style of living may, however, be a stressful lifestyle for both sharks.

If you want to keep more than one Red Tail Shark, it may be better to keep at least five sharks. You will need to add a meter to the tank for each shark.

Keeping at least five avoids having a dominant shark develop and reduces the amount of bullying that any one fish will have to endure.

Red Tail Sharks tend to chase any fish that moves into their territory. When housed with fish that are timid or when they do not have enough room to maintain a territory, Red Tail Sharks may chase other fish until they are exhausted.

Red Fin Sharks can Bully Other Fish

Red tail sharks tend to bully other fish

Red Fin Sharks tend to bully other fish away from food sources. Therefore, while they may not kill other fish by actively attacking or biting them, they may result in the death of other fish from sheer exhaustion and lack of food.

Since Red Tail Sharks tend to swim at the bottom of the aquarium, they may be most likely to bully other fish that swim at the bottom, such as plecos and cichlids.

Red Tail Sharks are happy to consume algae and leftover food that falls to the bottom of the tank, so your Red Tail Shark can likely replace the role of any other bottom feeder in your tank.

Why is My Red Tail Shark so Aggressive?

If your Red Tail Shark is behaving very aggressively, it is likely your tank size, decor, or tank mates that are at fault. 

  • In too small of an aquarium, Red Tail Sharks will territorially defend the entire aquarium. Other fish won’t have the opportunity to escape.
  • Without sufficient decor, Red Fin Sharks may expand their territory, so even an appropriately sized tank will not be big enough to reduce their aggression. Lushly planted tanks with plenty of decorations like driftwood may solve the problem.
  • Red Tail Sharks are typically aggressive towards most other sharks. They can also be aggressive to fish that are red or orange or fish that occupy the bottom area where the sharks prefer to swim.

Are Red Tail Sharks Fin Nippers?

Red Tail sharks tend not to nip at the fins of other fish, although they are very prone to chasing other fish. In the cases of fish that have fins that may resemble food, like betta fish or guppies, Red Fin Sharks may occasionally nip. Typically, however, they do not problematically bite at the fins of compatible tank mates.

Housing a Red Tail Shark – Aquarium Size

Are Red Tail Sharks Fin Nippers

Red Tail Shark size is relatively small, but nevertheless, Red Tail Sharks need fairly large aquariums, at least 55 gallons. If you want to house more than one, you will need a much bigger aquarium. In general, the larger the aquarium, the happier and more peaceful your Red Tail Shark will be. 

A larger aquarium enables your Red Tail Shark to establish their own territory and gives other fish space to avoid them or get out of their way. The more decor like live plants or driftwood you have in the aquarium, the happier a Red Tail Shark will be with less space, but no amount of decor makes up for the insufficient room. 

Red Tail Sharks generally do not disturb plants, so they are a good candidate for a well-planted aquarium. However, they tend to prefer dimmer lights, so plants that are tolerant of less bright light or enough plants to block out the light are necessary. Because Red Tail Sharks are strong swimmers that tend to stick to the bottom, a tank that is long rather than tall is best for them.

Do Red Tail Shark Jump Out of the Tank?

Red Tail Sharks will jump out of a tank, so any aquarium that they are housed in should have a lid. In fact, because they can jump with some force, the lid should be weighted to avoid the Red Tail Shark pushing the lid aside and jumping out of the aquarium.

It’s not a bad idea to cover any open areas such as where equipment goes into the tank with screen or another material that is firmly attached if it is a large enough space for them to jump through.

How Long Does it Take for a Red Fin Shark to Grow?

Red Tail Sharks will typically reach their adult size by about a year of age, provided they have a large enough tank. If they are kept in too small of an aquarium, it can stunt their growth, causing them to live shorter lives, have health problems, and never reach their adult size. 

You may be able to house a juvenile Red Tail Shark in an aquarium of around 30 gallons until they are about 6 months old, but be careful about housing them in such a small tank much longer as it may stunt their growth.

Red Tail Sharks are omnivores and scavengers

Feeding Your Red Tail Shark 

In the wild, Red Tail Sharks are omnivores and scavengers. They eat various insects, crustaceans, and all sorts of plants that fell into the rivers they frequent. They have a variety of sensors around their mouth which they use to sense potential food sources. Their variable feeding habits make them quite simple to feed in an aquarium environment. 

In captivity, they will readily take flakes or pellets. To make your Red Fin Shark as healthy as possible, consider supplementing their diet with live brine shrimp, blood worms, and other live food.

Large Red Tail Sharks may be able to take small feeder minnows. This sort of food is not only nutritionally dense but also causes lots of interesting activity from your Red Tail Shark. 

You can also suspend slices of cucumber or zucchini in the water for them to munch on, but be sure to take them out before they begin to rot.

Since Red Tail Sharks are happy to scavenge extra food from the bottom of the aquarium, they will help to keep the aquarium clean as well.

Size of the red tail sharks is Up to 6 in

Red Tail Shark Health Concerns

Red Tail Sharks tend to be very robust and quite healthy, but problems can happen.

  • Most of the time, when Red Tail Sharks develop health problem, poor water quality and speed is the problem.

  • Red Tail Sharks can develop ich and fin rot, especially when the water flow isn’t fast enough.

  • They tend to be pretty robust to water quality, but like any fish, they can succumb to health issues if the quality is very poor. 

Red Tail Shark Breeding

The vast majority of Red Tail Sharks in the pet trade are bred in captivity. Prior to this, their wild populations were significantly reduced by wild collecting. Red Tail Sharks are typically bred in large ponds, where a hormone is released into the water to stimulate spawning. 

Without the introduction of this hormone, it is extremely rare for Red Fin Sharks to breed in the home aquarium. Furthermore, Red Tailed Black Shark of both genders tend to be aggressive with one another, and few home hobbyists have enough room to house more than one Red Tail Shark.

How Can You Tell if a Red Tailed Black Shark is Male or Female?

It is difficult to tell the difference between a male and female Red Tailed Black Shark. However, sometimes females have a slightly more gray rather than black coloration.

Furthermore, females tend to be a little bit larger than males when fully grown. Females tend to have a more rounded abdomen than males. If fish are breeding, the female fish will have a more pronounced rounded shape during spawning time, but this is very unlikely in the home aquarium.

How Long are Red Tail Sharks Pregnant?

Red Tail Sharks are not live-bearing, so they are never technically pregnant. Sharks spawn and fry hatch within about two or three days. They are noticeably swimming around the aquarium after about four days.

Enjoy Your Red Tail Shark

Enjoy Your Red Tail Shark

Red Tail Sharks are fascinating aquarium fish that are relatively easy to keep under the correct conditions in the home aquarium.

As long as you avoid incompatible tank mates and provide plenty of room and decor, you will likely find that your Red Tailed Black Shark lives a long, healthy life and provides you with hours of entertainment in the home aquarium.

Common Red Tail Shark Compatibility Questions

Can a Rainbow Shark live with a Red Tail Shark?

Rainbow Sharks and Red Tail Sharks are both semi-aggressive fish, which may make you assume that they would do well in a semi-aggressive aquarium together. However, these two species do not coexist well.

Rainbow sharks should not live with Red Fin Sharks, as they will likely be very aggressive towards each other. They tend to become increasingly aggressive as they get older. These sharks may well fight to the death or create so much stress in each other’s life that they become sick over time.

Can you put a Red Tail Black Shark with Goldfish?

Goldfish are not good tankmates for Red Tail Sharks. They tend to be more docile, which means they may be bullied. Furthermore, Goldfish prefer a lower temperature range than Red Tail Sharks, generally between 68 and 74 degrees or 60 and 70 degrees, depending on the variety. 

Goldfish also prefer slower-moving water than what Red Tailed Black Sharks do best in, which can make it difficult for these two species to be compatible.
Red Tail Sharks can tend to be aggressive towards any fish that are red or orange, which can cause problems if they are housed with Goldfish. 

Can Red Tail Sharks live with Mollies?

Mollies are fairly peaceful fish that may be harassed by Red Tail Sharks. However, they tend to swim at the surface, so they may be able to stay out of the way of a Red Tail Shark. With plenty of cover and a large enough tank, it is possible that a Red Tail Shark could peacefully coexist with Mollies.

However, it is best to choose versions of Mollies that are not orange, as Red Fin Sharks are often more aggressive towards fish that are red or orange. If Mollies breed, expect Red Tailed Black Sharks to consume the offspring.

Can a Red Tail Shark live with Tetras of any kind? 

Red Tail Sharks generally do well with all different sorts of Tetras. Some of the best varieties are Cardinal, Glow Light, Neon, and Emperor Tetras. You may want to avoid glass tetras as they may be too weak to hold up to living with a Red Tail Shark. 

Because tetras tend to swim at the top of the tank and because they school together, they typically are able to avoid the territorial aggression of most Red Tail Sharks. However, keep in mind that if the Red Tail Shark is sufficiently larger than the tetra, it may consume them.

Can Red Tail Sharks live with any kind of Gourami?

Gouramis tend to be excellent tankmates for Red Tailed Black Sharks. They have a similar level of aggression and like to swim at the top of the tank, so they stay out of the Red Tailed Black Shark’s way. Some species also grow to about the same size as Red Tail Sharks. 

Dwarf Gouramis, Sparkling Gouramis, Pearl Gouramis, and Honey Gouramis are all good candidates for a Red Tail Shark. Other types may also work fine as well; just avoid red or orange color varieties as with any kind of Red Tailed Black Shark tankmates.


  1. Researchgate – link
  2. Sciencedirect – link
  3. Cambridge – link
  4. Wikipedia – link
  5. National Geographic – link
Jason Roberts
About Jason Roberts
Jason is an aquarium fanatic that has been a fish hobbyist for almost three decades.

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