MerlinSenger, CC BY-SA 3.0, via Wikimedia Commons

The Rainbow Shark fish, which is also known as the Epalzeorhynchos frenatum, is a small beautiful aquarium fish species that is loved by fish keepers from all over the world. This is one of the most beautiful fish species that display bright colors. It has many trade names, including the Ruby Shark, Red-finned Shark, Rainbow Shark Minnow, Green Fringelip Labeo, Whitefin Shark, and Whitetail Sharkminnow. But the Rainbow Shark is its most common trade name. 

It is one of the most popular aquarium fish species, known for its beautiful colors, and shape. The word shark in its name refers to the shape of this fish species because it appears as a mini version of the sharks. It is a passive-aggressive fish species, meaning that most of the time they would be peaceful but occasional fights, and skirmishes are also common. Also, it is not a shy fish species, meaning that if it is intimidated, it would fight back instead of running and hiding.

Its behavior, movement, color patterns, and beautiful shape make it an attractive fish species and that is why it is one of the most common aquarium fish species. This fish species is native to Southeast Asia and is found in Myanmar, Thailand, Laos, and Malaysia. It likes slow-moving, shallow waters, and is known for being a hardy fish species. This fish species likes the sandy bottom of the rivers where it feeds on phytoplankton and small insects. In its native habitat, it is known as a migratory fish species, because during the rainy seasons, this fish species moves from its home to other places.

Basic Facts Table:

LifespanUp to 8 years
Size6 inches
ColorsMultiple, depending on the subspecies. There are also some albinos.
Freshwater or SaltwaterFreshwater
Care LevelMedium,
CompatibilityPassive Aggressive

Tank Companions:

It is one of those fish species that are known for being aggressive. But it is not just an aggressive species, it is also a social fish. Meaning that you cannot keep it in a separate tank. Keeping a single Rainbow Shark fish in a separate tank would cause depression and anxiety in the fish and it can kill it. That means you will have to keep it in a community tank or a tank where other members of its species are present. It is recommended that at least 6 should be kept together.

Apart from that, you can also pair it with other fish species that are also of the same nature and same size. You can pair them with other shark species of the same size but you will have to make sure that you do not pair any of the bottom-feeding fish in the same tank with the Rainbow Sharks. It would be an extremely bad situation because this fish species can be extremely violent if its territory is violated. For that reason, it is recommended that you should only pair them with fish that do not dwell in the bottom of the tank.

Also, while deciding the tank companions for them, make sure that you put the tank companions of the same size in their tank. Otherwise, it would attack the smaller members of the tank and would try to dominate them. Also, if you paired them with small fish species of 1 to 3 inches, they might get eaten by the Rainbow Sharks because it is known for attacking and eating other fish of small size. That is also one of the reasons why it is known as the Shark.

Here is a list of the species that you cannot pair with the Rainbow Sharks. 

  • Some Rasboras
  • Large Danios
  • Large Gouramis
  • Loaches of the same size
  • Rainbowfish

Make sure that the fish you are putting are large enough to defend themselves if attacked. Although the chances of skirmishes are bleak because these are the fish species that mostly live in the middle or top layer of the tank.

There are also fish species that are not good companions for the Rainbow Sharks. This is because these fish species also have a similar habit of bottom-dwelling and it can cause conflicts inside the tank. Here is a list of the species that you cannot pair with the Rainbow Sharks. 

  • Bala Sharks
  • Red Tail Sharks
  • Most Cichlids
  • Most Catfish


It is one of the most beautiful fish species, it has multiple variants and each variant has slight differences. The Rainbow Sharks can have black, dark blue, or bright blue colors in its body. Some of these are also known for being colorless, or albinos. It has a pointed snout, with a flat abdominal area. Overall, their body is similar to sharks with a fin above their back. The fins of each variant have a different tint of red to orange. These fins are also partially transparent meaning that you can see through them.

In its natural habitat, it can reach up to 6 inches or 15 cm. That makes it one of the big aquarium fishes. Their black bodies with sharp reddish-orange contrast on fins make them appear beautiful. Some of these fish have an extremely black color, but some also have sharp blue and a tint of silver near the belly. It has large eyes that cover most of the face. This fish lacks any stripes over its body and in most variants the body has only three colors, one on the fins, one on the body, and one in the eyes and near the belly.

You will also see a difference between the body of the males and females in this species. You can identify the females and males by observing the colors of their fins. The ones with the brighter colors and more reddish or orange tones are the males and the ones with less reddish fins are the females. Also, there are some gray lines on the tail of the male members while female members lack these lines. Apart from color differences, you will also be able to notice a few differences in size, and shape of the bodies as well. For example, the bodies of the females are thicker and larger as compared to the males in this species.

1.   Albino Rainbow Shark:

It is one of the most famous variants or subspecies of the Rainbow Sharks. This fish is albino, meaning that due to some genetic modifications, its body lacks the color pigments. In this variant, the entire body appears colorless. But it reflects some pinkish color under the light and appears pinkish. Meanwhile, the fins in this variant are also bright reddish-orange. The eyes of this variant are also white and have pink corneas. It is the same species, meaning that care guidelines for the albino Rainbow Shark and the normal Rainbow Shark are the same. But, these are some of the rarest specimens. So, you will have to be extra careful with them.

2.   Glo-Rainbow Shark:

This one is a genetically modified patented subspecies of the Rainbow Sharks. It is a fluorescent fish species meaning that it emits colors from its body. You can buy it in the colors of your choice including purple, orange, and pink. It has similar body and care guidelines as the normal Rainbow Shark and the only major difference is in the color of the fish. If you are a fan of exotic fish, you should buy this genetically modified fish because it is currently one of the few that are being sold in the market.

Origin and Natural Habitat:

The Rainbow Shark fish is native to Southeast Asian countries, it is found in the shallow rivers, lakes, and ponds of Myanmar, Thailand, Laos, and Malaysia. This fish species is found in Mekong, Chao Phraya, Xe Bangfai, and Maeklong in Indochina river basin areas. All of these rivers flow from the mountains towards the Indian Ocean and create waterways where these fish like to live.

Contrary to its name, it is not a saltwater fish species like other sharks are. It is a freshwater species that lives in slightly acidic, warm, and slow-moving waters. This is usually found in those places where the bottom of the river is soft and sandy and contains a large amount of plankton and algae. It feeds mainly on these two. Apart from this, it also eats smaller fish species in its habitat and small worms, and invertebrates that it can find in the bottom of the river.

This is a migratory fish species and during the rainy season, it moves with the floods towards the flooded areas. But as the rivers move back after the floods and rains, it recedes to the river. This migratory behavior is very important because it is a part of their breeding cycle. But, in recent years, there have been a lot of developments on these rivers including the construction of various small and large dams. These construction projects have caused a drastic decline in their numbers because they are unable to repeat their breeding cycle and can’t go back once they move.

Rainbow Shark Lifespan:

The Rainbow Sharks’ maximum lifespan is 8 years. But most of them die before reaching this lifespan limit. This is because most of these fish are kept in poor environments. That results in the spread of diseases and infections that kills the entire population of these fish inside a tank. In their natural habitat, they can live up to 7 years and more but inside an aquarium, if the conditions are kept perfect they can live up to 8 years.

Their lifespan is dependent on the quality of life, meaning that if your aquarium has perfect conditions that support their growth, you will see that they can live up to 8 years. But if the conditions in your tank are not perfect, your fish species will only live for 4 to 6 years. Which is a significant reduction in the lifespan of Rainbow Sharks. So, if you want your fish to live longer and stay healthier, you should make sure that they are living in perfect conditions.

Habitat and Tank Conditions:

The health and well-being of your fish are attached to the type of conditions that you provide them inside the tank. So, you must make the right choices while creating a tank for the Rainbow Sharks. The first thing that you need to keep in mind is that this fish is big. It can grow up to 6 inches. That means you will need a tank that can accommodate a large fish. So, the first thing that you need to worry about is the size of the tank. There are a lot of different size recommendations for the tank of Rainbow Sharks. I would advise you to go for some of the biggest tanks. A large tank that can hold more water would provide more space for each of the members of your tank. This would significantly lower the chances of conflicts and skirmishes over territory. That means a large size tank can help you achieve a peaceful environment inside your tank.

Once you have selected the tank of the right size, it is time for you to start creating a habitat inside the tank for your fish. As these are bottom dwellers, meaning that they spend most of their time in the bottom of the tank. You will have to focus more on the bottom of the tank to provide them with a comfortable environment. Start by laying down a sandy substrate layer inside the tank. This would depict their natural habitat as the rivers where they live have a soft and sandy bottom.

You can also add some smooth gravel to make it look more natural. Make sure that you do not put anything edgy and sharp inside their tank at the bottom layer as it could hurt them. You can also put the plants inside the tank. You can put Anubias, Amazon sword, Hornwort, Java fern, Lemon bacon, and Vallisneria inside the tank for more greenery. These plants would help algae and planktons to grow and these two serve as a source of their food. You can also put some driftwood and ornaments inside the tank to create a more beautiful look.

Apart from these, there are essential items that you also need to put in your tank. These include a filtration system. You need a strong filter that can clean the entire tank within a few years. You will need to set the filtration rate 6 times. This would create enough movement inside the water that is ideal for this fish species. Also, it would help provide more oxygen to the fish.

Water Conditions:

Apart from the appearance of their habitat, you need to make sure that the chemical composition, temperature, and hardness of the water inside the tank are also similar to that of their natural habitat. You can do this by maintaining these parameters according to the needs of your fish. Below is a list of some of the most important parameters that you need to take care of.

  • pH: Neutral is better – 6 to 8
  • Hardness: 5 to 11 dH
  • Temperature: 24 and 27 °C (75 and 81 °F) (Room Temperature).

If you control these parameters, your fish would remain healthy and would live longer but if you failed to control them, your fish would die. For example, if the pH of the water is too acidic or basic, it would alter the internal chemistry of the organs of fish. Meaning that it would deteriorate its health and would kill it. Apart from that, if you are living in a cold region where the temperature can fall below zero.

You would need to maintain the temperature of the tank artificially otherwise, these cold-blooded fish would die. The same goes for the hardness of the water as well. Also, controlling the population inside the water is very important. If the water is not properly cleaned, it would create health issues. For example, parasites might get transmitted from infected fish to healthy fish and it could cause a widespread outburst of the disease in your tank. To avoid such a situation, keeping the tank clean is very important.

Water Source:

You can use water from any source but you will have to make sure that the water you are using is clean and is not polluted. Most water sources have been littered by human activity. Even our tap water contains several chemicals, such as chlorides that are used for killing bacteria inside the water to make it safe for drinking. But a higher concentration of these chemicals can give rise to algae blooms in your tank. Meaning that it has the potential to destroy the ecosystem of your tank.

For that reason, it is advised to use clean and purified water. You can use the water that has been filtered using reverse osmosis but make sure that there are no additional chemicals included in the water. There are a lot of water tests available that help determine the chemical composition of the water. These include pH meter sticks that can be used for checking the pH of the water. You can use these checks to make sure that the water you are using is safe for your fish.

Ideal Size For The Tank:

For the Rainbow Sharks tank, it is simple, find the biggest tank that you can. The larger the tank is the better it would be for your fish. They would have more space and you will be able to avoid skirmishes inside the tank. It is one of the large fish species, meaning that they need more space and water to swim and feed. So, you should pick a large tank.

You should pick a tank with a minimum of 30 gallons to 55 gallons capacity. Make sure that the tank is not taller but wider and rectangular. This would give your fish more space on the bottom layer because they are bottom dwellers, more space in the bottom is important for them.

Behavior and Temperament:

The Rainbow Sharks are known for being aggressive, territorial, bottom dweller, and slow swimmers but they are also known for being a social fish species. It means they like to swim with other members of their species and enjoy the presence of other fish in the aquarium. You might notice them chasing each other, but this is because they are playing with each other most of the time.

Fights only happen when you introduce them into the tank. They would fight to assert their dominance inside the tank. They would also fight to defend their territory. You will have to keep them in a large tank to avoid skirmishes. But still, they do not do very well in captivity and it has been reported that a lot of fish die within a year or two. But if you put them in a tank where there is large space and there are other members of their species. They can live for more than 4 to 6 years.

Breeding Rainbow Shark:

It is one of the hardest species to breed. This is because they have a migratory behavior and they breed during their migration time. In their native habitat, when the monsoon season starts and the plains are flooded. This fish moves from the river towards these flooded lands and comes back to the river to breed. But in captivity, you cannot replicate these situations, which is why it is hard to breed them.

Expert fish breeders who have had success at breeding the Rainbow Sharks recommend that you should pair a male and female inside the tank. There is a great chance that they would fight but eventually, if the conditions are right, females will develop eggs and lay them. Male would fertilize the eggs and care for them.

Eggs and Fry Care:

The eggs of Rainbow Sharks are dark and hard and once they are fertilized, it takes them about a week to turn into fry. Once the fry emerges, it starts to feed on its egg sac. It takes the fry about a month to properly learn to swim and feed inside the tank. You will have to protect them from both males and females. You can keep them in a separate breeding tank. Fry needs special care, meaning that you will have to feed them specialized fry food before they learn to feed on algae and normal food.

Diet of Rainbow Shark:

The diet of Rainbow Shark is an omnivore and in its natural habitat, it eats everything. In its natural habitat, it feeds on the algae and planktons at the bottom of the rivers. It also feeds on the green vegetation inside the rivers. This fish is also known for being a predator fish species. It preys on everything smaller and can fit inside its mouth.

Inside a tank, you will have to feed it a balanced diet to maintain its health. This balanced diet includes algae flakes, live insects, invertebrates, frozen meat, and crushed vegetables. You can create a proper diet chart and feed it according to that chart. Make sure to feed it the live insects and invertebrates now and then. It would help them get more protein.

Only pour a small amount of food inside the tank that it can eat in a few minutes. Also, put the food in larger chunks and make sure that the food you are putting inside the tank sinks to the bottom. This would help them get the food to the bottom of the tank. You will have to feed them twice every day. It is a large fish species that is why it needs more food.

Diseases of Rainbow Shark:

If the conditions inside the tank of Rainbow Shark are not according to set parameters, there are higher chances of your fish getting infectious diseases. For example, water pollution inside the tank can cause a lot of parasitic and bacterial diseases. So, you will have to make sure that you keep the conditions inside the tank right and keep the water in the tank clean. There are still some diseases that might affect your fish. Here is a list of the common diseases of Rainbow Sharks.

  • Constipation: This is a type of infectious disease that is caused by food. If the food is not of good quality, it can induce constipation. Long Term constipation can be a serious problem as it can shut down the internal organs of the fish and could kill it. It is a treatable condition and you can treat it with the help of proper medication.
  • Bloat: It is one of the most serious health issues in fish. In this disease, the body of the fish bloats and it causes trouble breathing and eating. It can also kill your fish. The first thing you need to do is to put your bloated fish in quarantine. Treat it with medicine, if it recovers you can put it inside the tank once again otherwise, you will have to clean the tank and get rid of it.
  • Dropsy: It is also one of the common fish diseases. Fluids accumulate inside the body and organs of the fish. It causes a similar condition to bloat but it is caused by different bacteria. If it happens, you will have to remove the fish from the tank and will have to clean your tank because it happens mostly because of the pollution inside the tank.
  • Ich (Ichthyophthirius multifiliis): Ich is also one of the common fish diseases that can attack the Rainbow Shark population. It is a treatable disease and you can cure it using specific medicines.

Are Rainbow Sharks a Saltwater or Freshwater Species?

Rainbow Sharks are freshwater fish species. Real sharks are saltwater fish, so when people hear the name of Rainbow Sharks, they think that these might also live in salt waters but it does not. They live in the rivers and lakes of southeast Asia.

Are Rainbow Sharks a schooling species or not?

No, it is not a schooling fish species.

Conclusion – Are Rainbow Sharks Suitable For Your Aquarium?

If you are a fan of beautiful fish species, then yes, these fish are suitable for your aquarium. It is one of the most beautiful fish species that have bright contrasting colors and a beautiful body shape. Apart from that, it comes in different varieties including Glofish, and Albino. Both of these varieties are rare and unique. All of these arguments are enough to say “yes” this fish is suitable for your aquarium.


Question: Are Rainbow Sharks aggressive

Answer: Yes, Rainbow Sharks are known for being aggressive towards other fish.

Question: What is Rainbow Shark’s minimum tank size?

Answer: The minimum size of the tank for the Rainbow Sharks is 30 gallons. You cannot use any smaller tank than this.

Question: Can Rainbow Shark live alone?

Answer: No, they cannot live alone for a long time. It can cause depression and the health of your fish would deteriorate. That is why it is advised to keep more than one rainbow fish in one tank.

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