A Beginner’s Guide to Rainbow Shark Care

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Bringing color, attitude, and uniqueness to your aquarium, the rainbow shark fish is a beautiful creature with an eye-catching appearance. 

Looking at one, it can be tempting to buy a new rainbow shark for your tank right there and then. Trust me, I have been there!

However, before you think of bringing a rainbow shark to its new home, there are a few things you should be aware of, such as the fish’s natural habitat, temperament, tank requirements, and much more.

In this beginner’s guide to rainbow shark care, we will go through everything you need to know before and after buying the fish.

Introduction to Rainbow Sharks

Rainbow sharks are often referred to as red-finned or ruby sharks, thanks to their bright red fins. The fish originates from Southeast Asia, and is native to tropical freshwater, instead of saltwater.

You will find these fishes usually living in rivers in Thailand, Malaysia, and Laos.

Despite what their name suggests, rainbow sharks do not actually belong to the shark family. They are given their name only because their dorsal fins have a shark-like appearance.

They belong to the Cyprinidae family and are classified as Epalzeorhynchos frenatum.

Appearance of a Rainbow Shark

The most prominent feature of a rainbow shark is, of course, its fins. Their fins are a rich red color and may even take on an orange hue at times. 

These vibrant fins tend to stand out even more against their dark (grey or black) bodies. Some of them even have a dark blue body. However, that is not so common.

Rainbow sharks have long and slender bodies. Their faces are somewhat flat, with a rounded snout in the front.

Their eyes – one on either side of their head – are a bit sunken in.

You may find that there are some color and appearance variations between the male and the female rainbow sharks.

Male rainbow sharks, for instance, tend to have brighter fins than their female counterparts. Moreover, male rainbow sharks tend to be slimmer whereas female ones are thicker and have rounder bellies.

These differences in appearances will be apparent to you once the fish mature as there are no noticeable differences in their looks when they are babies.

The Albino Rainbow Shark

Rainbow sharks also has an albino version that has identical red fins as the normal one but has a white or cream body rather than the usual grey or black one.

An albino rainbow shark’s body may seem yellow or light pink at times as well.

Coupled with the bright red fins, the light-colored body of the albino rainbow shark makes for an interesting combination due to which the fish is highly sought-after.

Albino Rainbow Shark

Rainbow Shark Size

When rainbow sharks hatch from their eggs, they are not much more than mere specks in size. From there, the fish grows somewhere between half an inch to an inch in size from two to four weeks.

At its full maturity, the average size of a rainbow shark is 4-6 inches. This applies to both males and females.


Rainbow sharks have an average lifespan of about 6 years but they may even live as long as 8 years. The lifespan of your fish depends largely on your tank conditions. The better the tank conditions, the more the fish will thrive and consequently, the longer it will live. 

Typical Behavior of a Rainbow Shark – Are Rainbow Sharks Aggressive?

Typically, the rainbow shark is a territorial fish. This leads to the fish exhibiting behavioral problems like aggression and dominance, at times.

The aggressiveness generally happens as the fish grows older. A young rainbow shark is usually very shy and prefers to spend most of its time in hiding.

Moreover, rainbow sharks are active swimmers. They swim at the bottom of the aquarium.

For this reason, they are also known as aquarium cleaners as they eat the algae growing at the bottom of the tank. 

Before you bring your new rainbow sharks home, you should make sure your tank is long and spacious for the fish to swim around in comfortably.

Rainbow sharks swim in higher waters, too. However, whilst they are peaceful with other fish in higher water, they are generally very aggressive with the fish at the bottom of the tank, including their own kind.

Their aggressive behavior can include anywhere from biting and head butting, to chasing the other fish.

To give them minimal reasons to get aggressive, you should place rainbow sharks in a tank with plenty of space and hiding spaces.

One more thing to take into consideration before bringing a rainbow shark home is jumping. Whilst they do not usually do this, it isn’t unheard of.

To be on the safe side, make sure your lid is well fitted to prevent the fish from jumping out of your aquarium.

Natural Habitat

Rainbow sharks come from the balmy rivers of Indochina having sandy substrates. They usually swim at the bottom of the surface of the water.

As mentioned above, the rainbow shark fishes are fast and active swimmers. They love to move around a lot in the tank and like their space. Therefore, getting a tank with a lot of horizontal space is necessary for these fish to thrive.

Typically, adult rainbow sharks should not be kept in tanks smaller than 50 gallons.

If the tank is too small for them, you are going to have a lot of territorial problems to deal with.

Ruby Shark or Rainbow Shark, epalzeorhynchos frenatus

Optimal Tank Requirements

Just like with any other fish, when it comes to caring for a rainbow shark, a few things need to be taken into consideration.

They do not need a lot of special care. However, I would not suggest beginner aquarists to get a rainbow shark. The fish is more suitable for people who have a few years of experience in this area.

To know rainbow shark care guidelines, read on below.

Tank Size

An average adult rainbow shark needs a minimum tank size of 50 gallons. This size would obviously increase as the number of rainbow sharks, or other fish, also increase. 

Rainbow sharks need space to thrive and live a healthy life. Therefore, anything smaller than 50 gallons would not be fair to the fish and would affect its health and the health of the other fishes around it.

Moreover, the tank should be at least 4 feet long. If you plan on keeping multiple rainbow sharks, then it should be no less than 6 feet in length.

Having a good-sized tank will also leave enough space to add rocks, plants, caves, and other substrates like sand, to the tank.

You should also leave a few inches of space on top of the tank to allow for oxygen to reach the rank. These few inches should be accounted for when looking for the ideal tank for your rainbow sharks.

The minimum tank size requirement of 50 gallons increases even more if you want to breed your rainbow sharks. This will provide the mating fish ample space to swim, hide, and enough gravel for the female rainbow shark to deposit eggs.

Water Parameters

If you want your rainbow shark to be safe and healthy, maintaining the right pH levels is vital. A pH level between 6.5 to 7.5 is ideal for the fish.

Remember to prepare your water and allow it to cycle for a couple of weeks (to stabilize it) before you introduce your rainbow shark into the new environment.

The water temperature should be set between 72- and 79-degrees Fahrenheit.

Make sure to place your new rainbow shark in the tank as soon as you reach home instead of letting it stay in the transport bag.

Tank Mates

As mentioned earlier, rainbow sharks dwell towards the bottom of the rivers they inhabit.

They imitate this behavior in captivity as well. Which is why you should avoid putting any other fish that tends to dwell at the bottom in the aquarium. Instead, go for fish that dwell in the middle or upper levels of the tank.

This would avoid any territorial issues and consequently, aggression among the fish.

The following fish could be safely kept along with rainbow sharks:

  • Rasboras
  • Gouramis
  • Rainbowfish
  • Danios

Conversely, these fish types are bad tank mate choices for rainbow sharks:

  • Redtail sharks
  • Catfish
  • Cichlids
  • Bala sharks

As a general rule of thumb, rainbow sharks are not usually aggressive towards other fish that don’t look like rainbow sharks or are rainbow sharks themselves.

Moreover, you should keep fish that are able to defend themselves from a rainbow shark’s attacks. You do not want to keep a smaller and weaker fish with rainbow sharks.

Compatibility With Other Rainbow Sharks

I would recommend you keep only one rainbow shark per aquarium at any given time. Rainbow sharks do not behave well when they have to live with their own kind and get aggressive as a result. This is because, in their natural habitat, they lead a solitary life and are not found in groups.

If you keep a larger rainbow shark with a younger/smaller one, they will relentlessly chase after the smaller one until it kills them.

However, if you still wish to keep multiple rainbow sharks, here are a few key points to keep in mind:

  • You should never keep 2 of them. Always keep 5 or more. This way the most dominant among them has multiple fish to chase

 Keep at least a meter of distance between two rainbow sharks at any given time.

Rainbow Sharks breeding

Nutritional and Dietary Requirements

Rainbow sharks are omnivorous fish, which means they eat both plants and animals. Thanks to this attribute, they are not fussy eaters and you won’t have to make a ton of effort to keep up with their dietary needs and choices.

In their natural habitat, they consume all kinds of decaying plants and algae. They also eat small chunks of meat such as Zooplankton, and insect larvae.

In captivity, they can eat:

  • Flake food
  • Frozen food (frozen bloodworms)
  • Vegetables (lettuce, spinach, zucchini)
  • Plants
  • Live food
  • Brine fish
  • Pellets
  • Tubifex worms
  • Insect larvae
  • Aquatic insects
  • Crustaceans

Given this long list, it would be easy to keep their diet varied. You should aim to provide them food from all sorts of food sources, similar to what they would eat in their natural habitat.

Providing them with a varied diet is going to ensure that they live a long and healthy life.

Keeping the dietary needs in the forefront of the fish becomes even more important when you are caring for young rainbow sharks.

If you want your juvenile rainbow sharks to grow large with vibrant red/orange colors, give them a diet that is diverse and not restrictive.

As for the frequency, you should feed your rainbow shark 2-3 times per day for about 5 minutes each time.

Rainbow Shark Breeding

Rainbow sharks usually mate from October through November in the wild. However, the exact month for their mating depends more on the length of the day and the temperature conditions.

Reproduction in rainbow sharks occurs through egg-laying. Once the eggs have been laid and the male has fertilized them, they will hatch within a week.

Keep in mind that breeding rainbow sharks in captivity is extremely difficult, if not impossible. The rainbow sharks you find available in shops are bred in commercial farms in Southeast Asia.

Is Your Current Tank Suitable For a Rainbow Shark?

Keeping a rainbow shark in your community fish tank would provide it with a burst of color like nothing else.

They can get a bit territorial as they mature. However, that should not stop you from getting a rainbow shark for your tank.

Given the right conditions and dietary requirements, the fish is going to thrive and would likely not cause any problems by getting aggressive.

The best part about keeping a rainbow shark is that they are not picky eaters and keeping up with their dietary requirements would be a breeze.

Whilst they are not the highest-maintenance fish out there, they are definitely not suitable for a beginner fish-keeping enthusiast.

You do need to take some extra steps to fully care for rainbow sharks. However, they make up for that in their beautiful appearance and fun colors.


Will Rainbow Sharks kill other fish?

Rainbow sharks are a semi-aggressive fish and can be very territorial so they will kill other fish if they do not feel safe and the tank is not big enough.

How many Rainbow Sharks can live together?

Each Rainbow Shark needs at least a meter of space in the tank. But if your tank is big enough then get a group of 5 so that the aggression can be dispersed among the group.

Can a Rainbow Shark live with neon tetras?

Yes, they should be fine as long as the neon tetras are not small enough to fit into their mouths.

Can a Rainbow Shark live with guppies?

A full grown Rainbow Shark might not be the best choice for slow moving guppies. If it is still a baby then the guppies should be okay but have a plan in place to move or re home the Rainbow Shark when it gets bigger. 

Can a Rainbow Shark live in a 20 gallon tank?

No, this size tank is too small for these active and semi-aggressive fish. They need at least a 50 gallon tank.

Can snails live with Rainbow Sharks?

Yes, they should be fine.

Do Rainbow Sharks need a filter?

Yes, for sure they do. They also like fast flowing water so they would also appreciate an additional power filter in there tank.

Will Rainbow Shark eat cherry shrimp?

Yes, they will so please do not let them be together.

Photo of author


Irma Bense is the founder of BetterFishkeeping.com. She has over 42 years of experience in keeping fish. She has kept both freshwater and saltwater fish through the years. She has extensive knowledge in breeding numerous species of fish from Show Guppies, Cory Catfish, German Blue Rams to Apistogrammas. You can learn more about Irma on the 'About' page.

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