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Featured Image Attribution: MerlinSenger

About The Red Fin Shark

Quick Summary:

  • Care Level: Easy-Intermediate

  • Temperament: Semi-aggressive

  • Max Size: 6″

  • Light: Medium

  • Temperature: 75°F to 81°F

  • PH: 6.5-7.5

  • Genus: Epalzeorhynchos

  • Species: E. frenatum

If you’ve been involved in fishkeeping long enough and no longer consider yourself a beginner to the hobby and believe you are ready to add something a little more challenging. 

Then you should consider purchasing a Rainbow Shark

The Rainbow Shark. is distinct in both its personality and its appearance and is popular among intermediate fish keepers.

In this article, we’re going to be discussing the many things this breed has to offer, as well as talking you through everything you need to know in order to adequately care for one.

Further Reading: Best freshwater aquarium fish

Equipment List To Help Care For Your Rainbow Shark

What Does A Rainbow Shark Look Like?

Ruby Shark

As you likely guessed from the name, the Rainbow Shark is one of the most visually pleasing freshwater fish available to mainstream aquarists.

The fish does not, however, feature a body of seven colors.

Instead, the common Rainbow Shark has a body of dark grey to black and fins of red to orange.

On paper, it admittedly doesn’t sound all that impressive, but the overall effect of the color scheme is quite striking and draws the eye directly to it.

You may also be interested in adding an Albino Rainbow Shark (an oxymoron, we know) to your tank.

Much like its more popular cousin, the Albino Rainbow Shark features fins that range from red to orange in color.

Unlike its more popular cousin, however, the Albino Rainbow Shark has a body that ranges from yellow to white.

If you were disappointed to learn that this fish does not come colored like a rainbow, you’re also probably going to be unhappy to learn that it is not, in fact, a shark.

While the Shark is a member of the Chondrichthyes family, the Rainbow Shark is a member of the Cyprinidae family, which also includes the goldfish, the common carp, and the common loach.

Here is the Rainbows Sharks full scientific classification:

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Epalzeorhynchos
Species: E. frenatum


Its name is derived not from its relation to the true shark, but from its upright dorsal fin, which gives it an appearance similar to that of the great white.

In adulthood, Rainbow Shark can reach up to 6 inches in length, with females boasting thicker bodies.

The male Rainbow Shark is thinner and brighter in color and can often be identified through black lines on its tail fin.

However, these lines generally only develop as the fish reaches maturity, which makes it virtually impossible to determine the gender of juveniles.


Red Fin SharkPhoto Credit: Aquarium Life

Rainbow Sharks are a pretty active breed and enjoy swimming, so you should seek to house yours in a tank that is large enough for it to move around comfortably (more on that later).

Although they may approach the middle and top of the tank – occasionally even jumping – they are primarily bottom dwellers and spend much of their time hanging around the aquarium floor.

As bottom feeders, these fish feast on algae and food left behind by other breeds, which makes them a popular choice of tank cleaner among experienced aquarists.

These fish aren’t the most aggressive breed in the underwater world, but they aren’t the most peaceful either.

Generally speaking, they can be housed in a community aquarium if the other fish in the tank spend their time towards the top of the water.

When they encounter other bottom dwellers, they may become territorial and aggressive and attempt to assert their dominance through chasing and biting.

Keeping more than one male Rainbow Shark in a tank is asking for trouble as males in the species are particularly aggressive towards each other and will almost certainly disturb their more peaceful tankmates with their fighting.

Compatible Tankmates

Because these fish can be aggressive towards certain breeds, you should do a little research to determine which breeds they are compatible with and which they are not.

Here are a few good tankmates for your Rainbow Shark:

  • Gouramis
  • Rasboras
  • Plecos
  • Snails
  • Barbs
  • Danios
  • Rainbowfish

Rainbow Sharks are one of the more territorial breeds of freshwater fish out there and do not take kindly to another fish entering their territory once they have claimed it as their own.

For that reason, you should avoid housing yours with other bottom feeders unless you have a particularly large tank that has room for both fish to steer clear of each other.

There are certain freshwater fish that prefer to live and swim in groups. However, this is most certainly not the case with the Rainbow Shark.

A solitary creature, it prefers to spend its time alone and does not play well with other Rainbow Shark.

In fact, it can be so temperamental that you shouldn’t even house it with fish that look like it.

If it lays its eyes on another Red Tail Shark, for example, it will attempt to assert its dominance as it would over its own kind.

If you are determined to keep multiple Rainbow Sharks instead of just one as advised above, you should try to stock your aquarium with at least five.

This is recommended because it means the dominant fish has multiple fish within its own species to bully and intimidate as opposed to just one. 

So each will have a little more peace and won’t have to worry about being chased constantly.

Tank Requirements

Just like caring for any fish, adequate Rainbow Shark care calls for an aquarium size that is suitable with the right set up.

As we previously noted, these are active fish and spend much of their time exploring their waters, so an aquarium size of no less than 50 gallons is essential.

Can a rainbow shark live in a 20 gallon tank?

A 20 gallon tank is not suitable for a Rainbow Shark. Any tank smaller than 50 gallons and your Rainbow Shark will likely become more aggressive than it has to be, tackling other fish in an attempt to claim what little space there is in the aquarium for itself. 

Click the image below to learn how to care for Ruby Sharks

How To Care For Ruby Shark

If you are planning on keeping multiple Rainbow Shark, which, just to stress again, is ill-advised, you’re going to have to make room for a tank that is capable of holding at least 125 gallons of water.

In an attempt to keep them from constantly confronting the other fish with which they are housed, many keepers of Rainbow Sharks fit their aquariums with plants and rocks.

This is advisable as plants and rock can provide your shark with another means of entertaining itself, distracting it, for a couple of moments, from its work oppressing its tankmates.

Along with plants and rocks, you should also fit your tank up with a couple of caves to give your Rainbow Shark a spot to hide.

Driftwood also makes a good hiding place and should be added to your tank if you have the room to spare.

Here are some basic tank settings:

  • Min Tank Size: 50 Gallons
  • Light: Medium
  • Temperature: 75°F to 81°F
  • PH: 6.5-7.5

What Do Rainbow Sharks Like To Eat?

As bottom feeders, these fish eat just about anything and provide a valuable service as tank cleaners, consuming the food left behind by their tankmates with little qualms about flavor or texture.

You should, however, make a constant effort to ensure your Rainbow Shark gets a varied diet and isn’t limited to one type of food.

Flake food and pellets are essential, as are vegetables, but you must also satisfy its omnivorous urgings, ideally with insect larvae, bloodworms, crustaceans, and brine shrimp.

Meat is particularly important when it comes to raising juveniles.

Without a steady intake of the foods mentioned above, a juvenile’s growth will be stunted and it will not develop the eye-catching colors that attract so many aquarists to its breed.

This diet should be maintained into adulthood, with two to three feeding sessions a day, to ensure your fish’s colors maintain their vibrancy.

So many good food options:

  • flake food
  • frozen food
  • pellets
  • algae (tablets or wafers)
  • insect larvae
  • crustaceans (frozen or live)
  • zooplankton
  • frozen bloodworms
  • brine shrimp

How often should I feed my rainbow shark?

You should feed your rainbow shark 2-3 times daily with a staple food such as pellets or flakes. Try to also feed them smaller crustaceans at least 2-3 times to bring out brighter and bolder colors.


If you’re hoping to try your hand at breeding, the Rainbow Shark is not for you.

Largely as a result of their aggressiveness, these fish are next to impossible to breed in an aquarium setting, with not even the most expert aquarists succeeding in their attempts to do so.

Because of this, no agreed upon guidelines for breeding in captivity exist for these fish.

It is safe to say any Rainbow Shark you purchase online or in a store was likely bred in a commercial farm in Southeast Asia, the species’ place of origin.

When mating does occur among these fish, the female will lay her eggs and allow her chosen male to fertilize them with a milt spray.

These eggs are then left to develop over the course of a week before hatching.


Because of its hostility towards other fish, the Rainbow Shark can be hard work for any aquarist.

However, the majority of those who have raised Rainbow Sharks agree that the trials and tribulations of doing so are more than worth it.

When housed with compatible tankmates, this little shark is a relatively peaceful creature and, though it may cause some trouble, is unlikely to disrupt your community too much.

With its effervescent colors and seemingly boundless energy, this breed will immediately catch the eye of all observers, hypnotizing them and allowing you to be proud to house it in your aquarium.

If you are looking for more options or more fish that look like sharks check out our article that lists 11 freshwater aquarium sharks that you can keep as pets.