Rainbow Shark – Care, Lifespan, Compatibility, & Behavior Guide

Last updated on December 24th, 2022 at 11:03 am

No doubt Rainbow shark is a unique and beautiful fish, and it will be an excellent addition to your tank collection. But some necessary things need consideration before getting one for your aquarium.

The Rainbow Shark is a misunderstood fish in aquariums, especially for beginners. So, it is essential to clear all of the facts and care sheet to clear out any misunderstanding about this beautiful aquarium fish.

We will explain this fish’s behavior, care, origin, and appearance. When you go through this guide, you will understand all aspects and get a solid understanding of Rainbow shark caretaking.

Rainbow Shark Overview

Scientific NameEpalzeorhynchos frenatum
Common NameRainbow Shark, Ruby Shark, Red Fin Shark
OriginSoutheast Asia
CaretakingEasy to Moderate
Body SizeUp to 6 inches
Feeding habitOmnivore
Movement TypeSemi-aggressive
LifespanUp to 8 years
Temperature Range24°-27° C
Minimum Tank Size50 gallons
pH Range6.5-7.5
Water type5- 11 dGH
BreedingModerate to Difficult
CompatibilityOther Freshwater Fish

Origin and Habitat

The Rainbow shark is native to Southeast Asia and is a red-finned or ruby shark. It is a freshwater fish that thrives in this water. You can find it in the rivers of Myanmar, Laos, Thailand, and Malaysia.

They love to live on the sandy bottoms of the river. During periods of heavy rains and flooding, they migrate into floodplains. Moreover, Rainbow sharks are not actual sharks, and this name is given to them due to their shape and appearance resembling sharks. They have dorsal fins on top, just like the real sharks.

This species was in plenty in the Southeast Asian waters, but they decreased in number in recent years. The damming of certain rivers, such as the lower Xe Bangfai case, dramatically impacts the number of rainbow sharks.

The dams on the rivers decrease the floodplains and may interfere with their breeding patterns. Moreover, their trade also affects the numbers because all the commercial rainbow sharks originate from farms in Thailand.

Rainbow Shark Appearance

Rainbow Shark Appearance

The rainbow sharks are known for their red fins and are named due to these beautiful fins. Sometimes this red color appears orange, making it unique. The body shape is very long and slender and usually black or grey. Red fin Rainbow Shark creates a beautiful contrast with its body, especially if they have orange color fins.

However, some rainbow sharks are dark blue but rarely present. This fish also contains beautiful shark-like dorsal fins with 11 branched rays and a forked tail fin.  

There are some color differences among the males and females from this color variation, and you can differentiate between their gender. The male has bright red or orange fins than the females, and there is a thin grey line on the male’s tail, but the female does not have this line.

The body of the female rainbow shark is a little thicker and round than the male. But note that all of these differences will be clear when both fish become mature; otherwise, before their adult age, they look the same, and no one can differentiate between males and females. So, wait for the right time until these fish become sexually mature.

Size of Rainbow Shark

When the Rainbow Shark is fully grown and matures, its size is no longer than 6 inches. But in some cases, Rainbow Shark max size reaches about 8 inches in length. However, this happens in rare cases, so the standard size is 6 inches in length. This size is almost equal for both the Rainbow Shark and Albino Rainbow Shark varieties. Male and females are nearly the same in size.

You can differentiate between a Rainbow Shark male or female from its size. Male contains mostly slender bodies than female. When these rainbow sharks hatch from eggs, they look like meager fragments. They are very tiny, but they grow faster and create a beautiful appearance.

Within two or four weeks, the fish become 1/2 inch or 1 inch in length. But they become mature and complete in size in several weeks or months. Generally, an average red-finned shark becomes sexually mature when it is 4 inches long, but it will grow after this, and the growth process will not stop.

Rainbow Shark Lifespan

If we talk about their lifespan, it is between 4 to 5 years, but some fish live long and may reach up to 8 years. But the stander life span is considered 6 years.

However, this is a good life span than the other aquarium fish, which may live only two to three years. But still, this time is much less than the goldfish, which can live in an aquarium for almost twenty years.

Many factors can affect the life span of your fish—the primary factor is the water conditions of your tank. If chlorine or chloramine is high in the water, it is essential to clean it with sodium thiosulfate. The cleanliness of water is vital for increasing the life span of rainbow fish and other aquarium collections.

Rainbow Shark Care:

Rainbow Shark Care

Some essential things should remain under consideration while having a rainbow shark. They consider tough little fish, and there is no need to baby them but no doubt that you need to take care of their essential requirements.

There are some instructions for care of rainbow sharks if you want to get them in your tank. If you follow these guidelines, you will give your red-fin sharks a good and healthy life.

1) Water Parameters

The correct pH level is significant so that your fish feel better in the tank. Rainbow Shark pH for water should be between 6.5 to 7.5. So, it is crucial to maintain this pH level.

If you want to transfer them to a new tank with a new environment, then it is vital to prepare your water and give it at least 2 weeks for recycling so that it has time to stabilize. Set the water suitable for Rainbow Shark temperature between 72 to 79 F°, and use a heater. It is important to feel them just like their natural habitat.  

When you bring your rainbow shark to your home, instantly place it in your tank. Try not to leave it in your transport bag in this way you can save fish from shock. When you immediately put it in your tank, rainbow sharks will get familiar with the aquarium environment, and the thriving process will be easy.

2) Tank Size

If you want to have a rainbow shark, I recommend you for a tank of 50 gallons at a minimum. A smaller tank will not be safe for them and other mate fish you want to keep with rainbow sharks. Because red-fin sharks need space to thrive, they also want to feel calm about their territory in the tank where they can live happily.

The tank size will be comfortable for them and at least 4 feet long and 18 inches wide if you want to keep one fish. The large tank will give room for a swim and provide them with space for separate areas. If they feel any restrictions, then rainbow sharks become aggressive and will harm other mates.

The vast tank will allow you to decorate it with rock and plants so that fish can hide in them freely and explore the tank quickly. You will leave some space of a few inches on the top of the tank to provide oxygen in the tank. So, keep in mind all of these requirements while setting up the tank, especially the tank capacity.

These fish feel like to cooped when you want to keep them in a smaller tank, and as a result, they tend to aggressive behavior and give a tough time to other fish. So, ensure that your tank is more than enough for space and keep a safe distance between the rainbow sharks and other tank fish.

However, if you want to breed rainbow sharks, this process is tricky because you may need a big tank if you mate these fish with each other. You will need a tank of 75 gallons while meeting the pair of red-fined sharks. This space is enough for scattering their eggs, hiding them, and an area for swimming all around the tank.

Rainbow Shark Compatibility

In the wild or their natural habitat, rainbow sharks like to live near the bottom of the rivers. So, in the tanks, they want to live near the bottom and have enough space to hide in caves behind the plants.

Rainbow Shark Compatibility

Avoid keeping the other mate whish and bottom dwellers when you want to keep a rainbow shark. There is a shortlist of the ideal tank mates for rainbow sharks:

  • Bala sharks
  • Redtail sharks
  • Cichlids
  • Catfish

It is better to choose the species that like to live in the middle or top of the tank. It is also better to have fish with good defense quality so that they can save them if there is any need. For this, good options are:

  • Rasboras
  • Danios
  • Gouramis
  • Loaches
  • Rainbowfish

We are not in favor of schooling fish because they also want to swim near the bottom of the aquarium so that it may become dangerous. However, barbs are exceptional as they have the same habitat and can adjust with rainbow sharks peacefully.

But the fact is that their semi-aggressive behavior can create any danger or risk with the other mates of your fish tank. But we have a solution for this, place the other fish in the aquarium first, then identify your rainbow shark.

Due to this, your rainbow shark will less likely consider this aquarium as their territory. The other solution is to add beautiful decorations for hiding ad provide them a feel of natural habitat. It will keep them busy and make less interaction with each other, and more minor the risk of attacking by the rainbow shark.

You will notice that this aggression will be less if a rainbow shark encounters the same size or more significant than its size. Rainbow Shark wants to rule small size fish and dominate smaller fish, but they are less likely to do that with same-size fish.

You will also see that they become more aggressive toward similar fish. That’s why red-tailed sharks will never be placed in the same tank to avoid any encounter in the aquarium.

Sometimes rainbow shark becomes aggressive with each other, and because of that, one fish wants to dominate the other fish. So, we recommend you place at least five rainbow sharks in a tank. It will restrict the one rainbow shark from dominating the other as the majority is the power, and no one will get picked on more than it should.

What do Rainbow Sharks Eat?

In their natural surroundings, they are omnivores and eat a lot of algae, and bite meats and larvae. But in aquariums, they like to eat algae at the bottom of your tank. You can also feed them algae in tablets, wafers, and flakes. They are algae eaters and, in this way, clean your tank from junk.

Most of the part of rainbow sharks depend on algae, and they need a balanced diet. There are some food recommendations for keeping them healthy and enjoying their food.

  • Frozen bloodworms
  • Fish granules
  • Bonefish
  • Insect larvae
  • Tubifex Worms
  • Crustaceans
  • Aquatic insects

If you want to add a variety of food for your fish, you can feed them chopped cucumber, spinach, and raw peas. This fish can also eat various plants and other animal materials. Avoid overfeeding them; you can provide them two or three times a day.

Careful about the feeding time of rainbow sharks, and don’t overfeed them. Give them simple food and take care of the quantity of food so that they can easily consume it. Under growing, rainbow sharks need more food for better health, and they need a different kind of vegetation to get the right and proper color when they become adults.

Are Rainbow Sharks Aggressive?

Now the most crucial question is about Rainbow Shark behavior. And most of the aquarists question whether will the rainbow fish kill the other tank mates. The answer is yes and no as well. Rainbow sharks can eat other fish, but mostly they eat vulnerable fish that unintentionally reach their territory. Otherwise, they will not pry on other fish or aquatic animals.

Are Rainbow Sharks Aggressive

The general behavior of Red-finned sharks is aggressive, and they can lose their temper when they look that their territory is in danger. So, you can say that they are entirely territorial, which leads to aggression.

Sometimes other bottom dwellers face an aggressive temperament because they like to live at the bottom of the tank. These redfin sharks are cleaner fish and eat algae and other substances from the bottom.

However, they are a good swimmer and like to swim all around the tank, and if they do not have enough space to swim, they will show aggression towards the other mates, even towards them in kind. In attack, they may harm the fins of other fish, bite their body, and even butt other fish heads.

Moreover, rainbow sharks like to hide in different places. So, for this, try to decorate your tank with plants and rocks. They also like dense vegetation so that you can make a bed of thick sand. If you want to keep your red-fin shark safe in your tank, keep it covered with a lid so that they will not jump out and harm themselves.

They like to jump, but you can overcome this habit by covering your aquarium with a lid. In this way, you can save them from jumping out.

Rainbow Shark Breeding

It is tough to breed Rainbow Fish in captivity. When you try to produce them, you will get a fight. They are aggressive and want to dominate the other fish and need to have an instinct hold on their territory for their influence. However, if they decide to mate, it is a big thing that they will become against each other. So, for hobby aquarists, it may become challenging to breed them.

After meeting, the females deposit the eggs on the substrate, and the male fertilizes them by realizing their milt. Eggs are hard and clear and take up to a week for hatching. When they hatch, the young ones absorb the yolk sac for a few days. In most cases, parents eat their fry, so it is good to keep them in a separate tank.

Rainbow sharks breed in South Asia on commercial farms. In these farms, hormonal injections can do the job of spawning due to their behavior. When produced on the farms, the juveniles become ready for trade for aquariums.

Due to their same physical appearance, it becomes difficult to differentiate between males and females until they reach adult age. They become ready for sext when they are 4 inches in length.

However, males are more vibrant in colors and look slenderer than females. The male fish also has black streaks on their tail fins, giving them an extra elegant look.

Caring for Rainbow Shark Fry

If you are an enthusiast and want to breed them in your tank, there are some instructions for a successful process. If you become successful in breeding, keep the fry in a separate tank. Ensure that thank is 10 gallons and contains a heater for maintaining a temperature. There should be plants in the tank for fry.

Transfer these eggs using a nylon net, and these eggs will hatch in several days. They use their yolk for sac, and after this, feed them liquid food for 1 to 2 weeks before giving them brine shrimp. Transfer them to the main tank when they are 0.5 to 1 inch long.

Rainbow Shark Disease

Rainbow Shark Disease

In expert view, this species is tough and sturdy, and they will remain safe from diseases mostly. However, they belong from freshwater, so they may suffer from freshwater diseases. But there is no need to worry about them, and you can cure them by keeping the water clean and taking medication.

There are some common diseases in rainbow sharks:

1) Bloat

Bloats appear due to the fluids, gas, or unpassed food present in the fish. They are not severe as look in the picture. You can notice a difference between a blotted fish and a fish that ate more. But the rainbow sharks will normally behave even if they overeat, but the other fish cannot hide the changes.


  • The stomach will blot without feeling any stretch in the scales.
  • You can notice it by the behavior of fish in activities. They will seem discomfort and avoid swimming.
  • The symptom is that your fish will not poop properly.


  • Constipation is the major problem
  • There may be a bowel blockage due to improper diet
  • Maybe there is an internal tumor or growth
  • There are perhaps any internal bacterial infections

2) Itching In Fish

Itching generally happens due to different parasites and appears like minor white marks or pimples on the fish’s body. It can attach to gills, bodies, fins, or mouths. When your Rainbow Sharks have this issue, you can see them scraping against trees, substrates, and other objects in the aquarium.


  • They scratch their body against the substrate and other things in the aquarium.
  • You will see white spots on the body of the fish.
  • The body will become red, and you can notice body streaks


3) Constipation

In most cases, constipation will clear on its own. But sometimes, you may need to give them a blanched fish diet to cure it. Daphnia or brine shrimp work well for constipation for both carnivores and omnivores. This diet will prove a painless treatment for your fish. Sometimes experts recommend you give a salt bath.


  • There is a blot in the stomach due to constipation
  • White and stringy feces
  • You fish look exhausted and stop their activities


  • If fish did not get fiber in the diet, then this would happen
  • HITH- Hexamita

Different types of antibiotics are available in the market for curing various diseases. But it is essential to use safe antibiotics for minnows, and the species belong to the Cyprinidae family. The best antibiotic is Prazipro.

You should avoid harmful things and don’t use Paraguard. The other things like salt, dyes, copper, and other dangerous substances. All of these things can create health issues for rainbow sharks. However, if your fish get the diseases, keep it isolated in another tank so that other tank mates will remain safe.

Due to their beautiful appearance and unique look, the hobbyists praise Rainbow Sharks. Their frequent rection and temper add extra marks. Their behavior and qualities will no longer make your tank activities dull.

If you want to add this fish to your collection, ensure that the water parameters, pH value, and hardness level remain controlled.

The most important thing to pay attention to is the right tank size. A spacious tank is necessary for this fish, and it will be 50 gallons in the minimum range. They can eat anything, so it is not difficult to feed them. But we did not recommend this fish for beginners. It is essential to get a little bit of experience before having this fish in your tank because you will get new experiences after having this fish.

Final Conclusion
Where Can I Find Rainbow Shark for Sale?

You can get these rainbow fish from a local fish store. It is a popular fish among aquarists. The Rainbow Shark price is about USD 9 or less because they are considered the centerpiece fish, and that’s why it is not so expensive.
Most of the tanks can keep one rainbow shark, so avoid getting the school of fish. But before buying this fish, reconsider your tank setup and the size of the tank for accommodation.

Is a rainbow shark a real shark?

Rainbow sharks are not actual sharks. They are only related due to their appearance. They are more related to carps and minnows than sharks. However, rainbow sharks belong to the Cyprinidae family, while the great white sharks belong to the Chondirichtheyes family.
But their physical appearance, long slender body, pointed snot, and fins make them just like sharks and make them different from their family.

Leave a Comment