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Home Lifestyle Rainbow Shark: The Complete Guide

Rainbow Shark: The Complete Guide

Having a splash of color in your aquarium is a definite advantage for many fish enthusiasts. Luckily, the rainbow shark fish variety does the job for you. The rainbow shark adds color to your aquarium. It also offers an interesting dynamic on how it relates to other fish in your aquarium.

The rainbow shark is not an actual shark. It is also not part of the Chondrichthyes family (where sharks belong). It comes from the Cyprinidae family. This fish family has small and attractive freshwater fish like the minnow.

In Retrospect

The rainbow fish comes from the rivers of Southeast Asian countries. They are popular in Thailand, Laos, and Myanmar. But because it breeds fast in its natural habitat, it is accessible worldwide.

They are more comfortable in an environment filled with plankton and sandy bottoms. The rainbow shark also leaves their bases during typhoon season. They choose to stay somewhere safe, like a floodplain.

The rainbow shark has many names, some of which include ruby shark and red-fin shark. They have these names because of their famous vibrant red fins that make them stand out from the rest!

Let’s Dive In!

There are many misconceptions about the rainbow shark. True to their name, they can be a tad bit aggressive and territorial. This makes it difficult for them to interact with other fish in your aquarium.

I would recommend more experienced fish enthusiasts to handle these types of fish. Beginners can also do so as their care levels are bordering between easy to moderate. With a little bit of research, you can spruce up your aquarium in no time!


The rainbow shark is a stunner when it comes to fish species. Their long and slender body is dark gray. But what makes them stand out is their vibrant red fins, hence the name rainbow shark or ruby shark!

It got its name because of its dorsal fin on top, making them appear like a small shark. Their fins also have bright orange to blood-red color. This makes them stand out even more against their long and slender gray bodies.

Astonishing Attributes

Their fins are also unique! If you can look at their fins, you can count to 11 branched rays that end with their forked tail fin. This fish’s face is flat and unremarkable with a pointed snout. They appear to have sunken eyes, but their long and slender body rounds off a bit and tapers off towards the end.

The rainbow fish can grow up to 6 inches at their peak. It is one of the most attractive freshwater fishes there is!

Distinguishing Features

Variations between males and females also have a slight difference. It is difficult to determine whether the rainbow fish is male or female early at an early stage. You must wait for them to mature.

Males have brighter fins than the female species. Males will also have gray lines on their tail fins, while females do not have this characteristic. Females also tend to be rounder and thicker in their bellies. Males are more slender and thinner as compared to their female counterparts.

Did You Know?

The rainbow shark also has an albino counterpart. The only difference is instead of the fish having a dark gray body, its body is white. There is no difference in the color of its fins. The albino variant still has the orange to bright, red-colored fins which they are famous for.

Typical Behavior

The rainbow shark is an aggressive and territorial fish. But, there are many ways for you to control their aggression. In its natural habitat, the rainbow shark appears to be quiet and timid.

They are not perceived to be predators and would go on living their own life. They are bottom-dweller fish and eat algae, which makes them good at cleaning the water.

Helpful Tips

But the same is not true when they are inside a fish tank or aquarium. They are semi-aggressive fish. Head and tail butting, threats, biting, and fighting are likely to occur. These types of fish will attack smaller fish to the tank, including their own.

Fish jumping is also expected to occur. To reduce these kinds of behavior, I would recommend that you have a small fish-to-water ratio in your tank.

I would also recommend you have a large tank. The tank should also have hiding places such as caves, tunnels, and other hollow spaces. This will reduce the rainbow shark’s aggressive tendencies.


Rainbow sharks can grow up to six inches. During their first month, the rainbow fish will grow half an inch in size. It would usually take them a few months to reach their full size of up to six inches.

They are also known to have small and slender bodies. Females have thicker and rounder bellies than males when they mature.


The lifespan of a rainbow shark ranges from five to eight years. Of course, this depends on the level of care you provide to your rainbow fish. Rainbow sharks are semi-aggressive fishes. If you have a smaller fish in a tank, this helps reduce their aggressive tendencies.

You should include hollow décors, caves, and other aquarium décor in the tank. In this way, that will allow them to hide and reduce their aggressive tendencies.

Rainbow Shark Care

  • The care requirements of rainbow sharks are easy to moderate. Here is an overview of the care requirements of rainbow sharks. Do note we will discuss this in detail in the succeeding sections.
  • The tank requirements for a rainbow shark should be rectangular that can fill up to 50 gallons. This is important since these types of fish are semi-aggressive. They need space to avoid fights and aggressive behaviors.
  • The location of your tank is as important. Ensure that you find them a safe and secure place. I would recommend a place away from busy activity. You also need a place that does not have extreme exposure to weather conditions. Rainbow sharks are bottom dwellers. Thus, they may feel stressed if they are in a place with too much activity.
  • Put sand in the bottom of the aquarium. As much as possible, it would be best if you mimicked their natural habitat. Rainbow sharks are more comfortable with sandy bottoms.
  • Rainbow sharks are omnivores; hence you need to feed them a diverse diet.
  • Tank maintenance is also a must when it comes to taking care of your rainbow sharks. Since these types of fish clean the water themselves, you can choose to clean the tank every week.
  • Rainbow sharks are semi-aggressive sharks who can attack even their species. This is why you should be careful when introducing tankmates. Avoid putting other bottom dwellers in the same tank. They can be aggressive towards them.
  • Provide ample space for your rainbow sharks to hide in. This will help reduce their aggressive tendencies.


Rainbow sharks are omnivores. This means that they are not picky eaters – they can eat both plants and animals. They have a particular liking for algae. Their diet consists of algae, leftover fish, decaying plants, and even planktons!

Because they are bottom dwellers, they will eat anything that falls in the bottom of the tank. Rainbow sharks should have a varied diet. For example, you can feed them one day of algae tablets or wafers. The next day, you can provide them with insect larvae, feed them with frozen or live crustaceans, and so on.


You can also feed them vegetables such as zucchinis, peas, lettuce, and spinach. These types of vegetables can help strengthen their immune system. Your rainbow fish should also have a varied diet. This is especially true in their early years so they can grow faster. Also, this is so their red-colored fins will come out strong and vibrant.

Another pro-tip to bring out the best color of their fins is to feed them with lots of protein. This includes frozen meat like frozen bloodworms and brine shrimp.

Tank Mates

Do not put your rainbow fish with other bottom dwellers’ fishes. Examples include Bala sharks, red tail sharks, cichlids, and catfish. This is a sure recipe for chaos. The rainbow fish will protect their territory and attack them and chase them. In extreme cases, other fish have no choice but to jump out of the tank.

Do not also include smaller and more timid fishes in the tank as they will terrorize these poor fishes. Instead, choose middle or top-dwelling fishes. They will have lesser chances of interacting with the rainbow fish. Danios, gourami, rasboras, and loaches are good tankmates for your rainbow fish.

Common Health Issues

Rainbow sharks are pretty resilient when it comes to diseases. The most common health issues include Ich and Swim Bladder Disorder. Fungus and Skin Flukes are also very common. You need to be on the lookout for any signs and symptoms of illness in your rainbow shark. If you see any of these, call a vet and have your fish treated.

One of the most common causes of health issues among rainbow sharks is water quality. Rainbow sharks are sensitive when it comes to water quality. This is why you need to check the water through the thermometer and testing kits.

Best Tips

You should also avoid using salt, copper, and dyes when treating your water. This is because rainbow sharks are freshwater types of fish. They do not respond well to these types of water treatment. Do not use Paraguard. This is a pest control solution for aquariums. Some of the ingredients used will harm your rainbow shark.

While it is important to feed your fish a varied menu, please do not overfeed them. This will lead to health complications. If your rainbow fish is sick, focus on providing them protein and fresh vegetables. This will allow them a fast recovery.

It is also recommended that you put them in a separate tank when they are ill. They can be extra aggressive and attack other fish during this period.

Rainbow Shark Breeding

There is no documented successful breeding of rainbow sharks in an aquarium setting. This is due to their aggressive nature. In their natural habitat, female rainbow sharks lay 5 to 7 eggs a day that can hatch in less than a week.

Southeast Asian commercial farms are also known to breed them.

What Size Aquarium Do They Need?

You would need a large, rectangular-shaped aquarium that can fill water for up to 50 gallons. In this way, your rainbow fish and other tankmates will have enough space to swim. They will also not attack or chase one another.

I would also recommend you fill your tank with caves and hollowed décor. This will reduce the aggressive tendencies of your rainbow shark.

How Much Water Per gallon?

I would recommend for you to buy a tank that can at least fill 50 gallons per tank.

Compatibility With Other Fish

I would recommend for you to put other middle dwellers or top dweller fish in the same tank as your rainbow fish. Do not, under any circumstance, fill your tank with other bottom dwellers. Remember that rainbow fish are territorial and aggressive. They will chase and attack these poor bottom dwellers. Some might even jump out of the aquarium to escape.

At The End Of The Day

Rainbowfish is one of the most beautiful aquarium fish for your tank. While they are beautiful, it can be a tad bit difficult to integrate them with other fish in your tank. They are aggressive towards bottom dwellers.

Make sure you put them in a tank with other top and middle dwelling fish. You also need to make sure that you decorate your tank with caves and hollow areas so they can hide.

Nonetheless, caring for rainbow sharks is a rewarding experience. The article above will help you know more about the rainbow fish. It should also help you learn about its care requirements. This will make you successful in caring for your rainbow shark.



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