Rainbow Shark: Ultimate Guide (Care, Diet, Breeding & More)

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Written By Matt Stevens

Hi, I'm Matt! I've been obsessed with fishkeeping for over 15 years now and created this site to share my knowledge with others.

No! They don’t possess all the seven colors of the rainbow, and they are not even true sharks.

But they are one of the cutest freshwater fish you will ever see in a home aquarium. Rainbow Sharks are an incredible addition to any aquarium.

They are neat, incredibly active, and distinct-looking. And if you choose to keep the Ruby Sharks at home, you won’t be disappointed by their colorful look and attitude that has made them very popular in the fishkeeping community.

Rainbow Sharks might be notorious for their semi-aggressive temperament, but their ability to peacefully coexist with larger fish species readily compensates for their slight downside

If you’re looking for a picture-perfect species to add some vibrancy to your tank, you shouldn’t ignore these little sharks.

In this guide, we will discuss their care guidelines in detail. Specifically, we will cover their unique dietary requirements, appearance, tank mates, common diseases, tank size, breeding, and more!

Species Overview

Rainbow Sharks are native of Southeast Asia, and are sometimes called Ruby Sharks, Red Finned Sharks, Rainbow Sharkminnows, Whitefin Sharks, Green Fingertip Labeos, and Whitetail Sharkminnows.

Don’t confuse them with the normal saltwater fish because they are nothing close to the highly aggressive and man-eating sharks. They are small freshwater fish that have been located in specific rivers in Laos, Malaysia, Thailand, and Myanmar.

ColorGray, Red
Lifespan5-8 Years
Care LevelEasy/Moderate
Behavior & TemperamentSemi-aggressive
CompatibilityModerate. Gets along with many other freshwater species.
Food and DietOmnivores
SizeUp to 6 Inches
Tank SetupTropical Freshwater: Plants, rocks, caves
Tank Size (Minimum)50 Gallons

Throughout this region, these fish thrive in rivers characterized by sandy bottoms and lots of plankton to support their dietary needs.

Typically, Rainbow Sharks represent the species in the Cyprinidae family under the order Cypriniformes. The most popular species in this family are minnows.

Like many freshwater sharks kept at home, many aquarists believe that the damming of rivers throughout Southeast Asia has led to the decline of the Rainbow Shark population in this region.

In terms of care guidelines, we see Rainbow Sharks as a special fish with unique requirements and, as such, should be kept by seasoned aquarists with some prior experience in fishkeeping.


A typical Rainbow Shark has a lifespan of 4-6 years.

It’s worth reminding that Rainbow Sharks are sensitive to high levels of chloramine and chlorine in the water. So, if you choose to keep them at home, the first step to increasing their lifespan will be to provide high-quality tank water.

You should consider treating the tank water with sodium thiosulfate or Amquel to control the chlorine levels in it.


Rainbow Sharks are known for their neat look that’s facilitated by their beautiful, red-colored fins. However, you may notice shades of orange in some species.

The red-colored fins perfectly complement their naturally streamlined body shapes that can always take black or gray coloration. Dark blue Rainbow Sharks are quite rare to see, but you shouldn’t be entirely surprised if you spot one at a local pet store.

The “shark” given name results from the fish’s shape. Usually, the upright dorsal fins mimic the ones in saltwater sharks and are the first observation you will make regarding the fish’s distinctive look.

What’s more, Rainbow Sharks have a flat face with a well-rounded snout, perfectly complimenting the frontal shape. Of course, these fish have two eyes with a neatly rounded body, appearing to taper off towards the tail.

Color variation highlights the slight differences between male and female Rainbow Sharks. For instance, the males have more vibrant orange or red fins than the female species. Also, thin gray lines on the tails are only noticeable in the male species.

Finally, female Rainbow Sharks are easily noticed due to their thick, well-rounded bellies compared to the males.

It’s hard to differentiate the male and female species in juvenile fish. But everything gets clearer as the fish approach maturation.

Types of Rainbow Shark

Let’s talk about the Albino Rainbow Shark:

Albino Rainbow Shark

A unique variety of the Ruby Shark is the Albino Rainbow Shark, easily recognized by its white appearance in place of black or blue markings.

Despite maintaining the red or orange fins like the traditional Rainbow Shark, the Albino varieties have beautiful white coloration which matches the name.

At times, the albino variant of the Rainbow Sharks will have yellow shades or a light pink hue. Its unique appearance is spot on if you want to add a special color to your home aquarium.

But everything else remains the same. Like conventional Rainbow Sharks, the Albino variant of Ruby Sharks are also known for their territorial behavior.


Generally, Rainbow Sharks have a moderate to slow growth rate and may take a couple of weeks or months to reach full maturation.

A typical Rainbow Shark will be about 6 inches long in maturity. But under rare circumstances, they can grow up to 8 inches. There are no apparent differences between the male and female fish when it comes to size.

Rainbow Shark Care

Rainbow Shark care is interesting if you know the actual conditions in their natural habitat.

Usually, providing quality care to the Red Finned Sharks starts with giving them enough space in the tank for swimming and relaxation. But we will discuss that in the next section.

On top of that, these fish require sufficient oxygen inside the aquarium, which you should factor in when designing the tank.

Rainbow Sharks are easily startled when cramped in the same space and show their semi-aggressive trait when kept in a small tank. So, you must ensure the designated tank promotes their health and comfort at home.

Moreover, Rainbow Sharks tend to spend a lot of time at the bottom half of the tank. And as such, they need plenty of vegetation, tunnels, and caves as the ideal hiding areas.

Tank Size

Rainbow Sharks will be satisfied with an average tank size of 50 gallons for every species. Assuming you will be keeping more fish in the same aquarium, you will need significant size to accommodate the entire school.

There’s no right or wrong way to set up the ideal tank because everything depends on the number of fish you keep in the same aquarium. However, smaller is not necessarily better when it comes to Rainbow Shark care in the home aquarium.

We’ve always encouraged aquarium enthusiasts to focus on the horizontal space when setting up their tank because it is the easiest way to control the Rainbow Shark’s territorial behavior. So, anything below 18 inches in width with a length of 4ft won’t be ideal for your fish.

Water Parameters

Now, let’s talk about the water parameters.

Firstly, pH imbalance is unheard of in a Rainbow Shark community. That’s why you should always aim at maintaining it at the standard levels of 6.5 to 7.5.

Before introducing Ruby Sharks into a new aquarium, many aquarists will spend enough time (at least 2 weeks) preparing the tank water until it has completely stabilized. And perhaps you will want to use the same method before maintaining stable temperatures at 72°F to 79°F.

The last aspect you will want to address is water hardness, which is just as important for Rainbow Shark care. This should never go beyond 11dh, even when the ideal range lies between 5 to 11dh.

What to Put in Their Tank?

Because of their territorial behavior, Rainbow Sharks require plenty of hiding spots to ease tension inside the aquarium. This is especially important if you intend to keep them with other fish species in the same aquarium.

In that regard, you should introduce rocks, plants, driftwoods, and caves as part of tank décor.

Having plenty of vegetation inside the aquarium will distract your fish from time to time and prevent possible conflicts from their territorial behavior.

In terms of the right substrates, you will want to mimic the exact conditions in Asian rivers. And smooth sand is perfect for Rainbow Sharks in captivity.

Gravel should be cautiously used because they carry a huge risk of injuring these fish in home aquariums. And if you have to include them as part of tank décor, be sure to get the finest forms.

In conclusion, ensure the top of your aquarium is properly sealed because Ruby Sharks are not just active swimmers. They are escape artists who may leap out of the tank easily without close monitoring.

Common Diseases

Luckily, Rainbow Sharks are hardy fish species that won’t succumb to many ailments affecting the freshwater fish community.

Nevertheless, it’s important to watch out for potential symptoms linked to specific conditions such as Ich, skin flukes, fungus, and swim bladder disorder.

The most common cause of disease in Ruby Sharks is reduced water quality. And you can maintain everything at the required levels by monitoring the key parameters we’ve already covered above.

You can adopt simple strategies to help prevent common diseases in these fish. These include testing the water regularly to confirm its status, changing the tank water occasionally, and avoiding overfeeding.

If you have to treat your fish for any of the common ailments, avoid any medications with copper elements, dyes, and salts that could have adverse effects on the entire fish community in the long run. You should only consider drugs that are safe for the entire Cyprinidae family.

What Do Rainbow Sharks Eat?

Do Rainbow Sharks eat algae? You may be wondering.

Well, Rainbow Sharks aren’t fussy eaters, to say the least. And as omnivores, they eat plenty of algae, meat, and larvae in the wild.

When in captivity, they will naturally like algae, which is part of their diet in the wild, after all. Aside from that, you can supplement their typical meal with wafer forms or flakes to provide additional nutrients.

You can adopt a diversified approach to ensure these fish get all the essential nutrients they need from popular food sources. This means that you can go with different healthy food choices instead of limiting your fish to just one meal.

For protein sources, aquatic insects, crustaceans, tubifex worms, frozen bloodworms, insect larvae, fish granules, and brine fish are good options.

If it’s vitamins, you can pick common vegetables such as raw peas, spinach, and blanched cucumber while studying the fish’s eating habits.

But watch out for overfeeding. It is one of the most common causes of improper digestion and fin rot in freshwater fish, like the Rainbow Shark.

Experts say that you will learn more about Rainbow Sharks in their juvenile stage than you ever will throughout their lives. And it’s easy to see why. The youthful period is the most critical stage to address the fish’s unique dietary needs. 

At this point, Rainbow Sharks will be more active and will require a high-quality diet to grow and maintain their spotless color pattern.

You may want to review the care guidelines if you notice a baby Rainbow Shark with stunted growth and discolored fins. Because chances are, you are feeding them low-quality food.

Behavior & Temperament

So, are Rainbow Sharks aggressive? Well, we can say they are the true definition of semi-aggressive freshwater fish.

And this trait will be more pronounced if you keep them in a small tank or introduce other fish in the same aquarium. They tend to show their territorial behavior when kept with smaller fish species.

The easiest way to counter the Rainbow Sharks’ partial aggressive nature is to introduce natural hiding spots such as plants. The general belief is that they won’t attack the smaller fish if they don’t see them.

Sometimes it works. At times it doesn’t. Still, plenty of vegetation is mandatory to keep everyone safe inside the tank. Also, you can counter the Rainbow Shark’s aggression by introducing larger fish species in the same tank.

Some aquarists have reported aggressive behavior in them if they spot other fish that resemble them. This includes Red-Tailed Sharks that never make great tank mates for Ruby Sharks.

While overcrowding is highly discouraged, keeping two or three species will only see one fish asserting their dominance over the rest. That’s why it’s highly recommended to keep at least five fish if you have enough resources.

Rainbow Shark Tank Mates

Rainbow Sharks are bottom dwellers in their original habitat. So, keeping them with fellow bottom-dwelling fish is a recipe for disaster. This means Rainbow Sharks won’t be ideal tank mates for Bala Sharks, catfish, cichlids, and Red Tail Sharks.

On compatible tank mates, Rainbow Sharks tend to live peacefully with fish species that spend most of their time towards the top of the tank and with the ability to defend themselves if needed. This group includes any of the following:

  • Gouramis
  • Rainbowfish
  • Loaches
  • Danios

Schooling fish won’t be ideal Rainbow Shark tank mates because they will want to occupy the same space in the tank.

Interestingly, despite being bottom dwellers, barbs have been known to cohabitate peacefully with the Rainbow Sharks.

Of course, most of the peaceful fish in your home aquarium won’t love your Rainbow Sharks. And it’s all because of two reasons; dominance and aggression.

So, if you introduce Ruby Sharks at home for the first time, you need to prioritize other fish and only introduce the cute little sharks when everyone else has settled. This strategy prevents the little sharks from gaining dominant control over the rest.


We will be honest with you here. Breeding Rainbow Sharks in a confined setup can be challenging for many reasons.

The first thing you must consider when trying to breed these fish is the tank size. Usually, a larger tank of at least 75 gallons is required for successful breeding.

It’s safe to assume that Rainbow Sharks aren’t sexually mature until they are 4 inches long.

Like many fish, the females will begin the breeding process by laying eggs to be fertilized by the male species. Then, the eggs will take about one week to hatch.

If you think about their aggressive nature and territorial behavior, you will understand why breeding these fish in captivity is almost impossible.

Most of the Ruby Sharks in pet stores originate from commercial farms in Asia, where hormones facilitate breeding.

Final Thoughts

With what we’ve covered in this guide, you should now be comfortable keeping Rainbow Sharks in your home fish tank.

Despite their slight behavior issues, we can all agree that keeping Rainbow Sharks at home is rewarding for many reasons.

You won’t get enough of their colorful look, agility inside modern aquariums, and effortless care requirements.

If you have everything in place, why not give it a try and see how the beautiful Rainbow Shark will transform your tank in just a few months!