Rainbow Shark Care Guide, Feeding, Breeding & Tank Mates

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The Rainbow Shark is an incredible-looking fish, although not always the easiest to look after. It is however worth the effort, this guide will teach you how to care for them and what other fish will make the best tank mates. 

The Rainbow Shark is a great looking fish, how easy is it to look after though, what does it eat, how compatible is it with other fish?

The Rainbow Shark is probably not the easiest fish for beginners but it can be worth it, since it looks so good. If the research is done, you can find the right tank mates such as Tetras. This fish is a bottom feeder so pellets are a good choice of food, as well as them eating algae.

I spent a decent amount of time researching the Rainbow Shark, you can find a complete guide on this below

Rainbow Shark Quick Stats

Experience Level: Beginner/Intermediate

Minimum Tank Size: 50 Gallon

Family: Cyprinidae

Diet: Omnivore

Size: 6 Inches

Temperament: Semi-Aggressive

Water Temperature: 72–81° F (24–27° C)

PH Level: 6.5-7.5

Lifespan: 8 Years

Introducing The Rainbow Shark

Image introducing what the Rainbow Shark looks like

If you want to add some extra color to your Aquarium, the Rainbow Shark might be an excellent choice.

These fish are also commonly known as Ruby Sharks and RedFin Sharks, even though they are not actually sharks.

They are native to Thailand and are tropical freshwater fish.

As mentioned it’s not actually a shark, it gets this name because of the look of its fins resembling that of a shark. 

The main body of the Rainbow Shark is black with bright red fins and will typically grow up to 6 inches.

They do make good community fish, although as they are territorial you should keep the numbers of sharks to a minimal. It’s also very important to have plants to help them hide if they need to.

Basic Care

Compared to some fish the Rainbow Shark is not the easiest to care for, which is why many recommend some aquarium experience before getting one. You are going to want a tank of at least 50 gallons, giving it plenty of space to swim around. It is possible to have a couple but you are going to want a much bigger tank, 125 Gallons would probably be ideal.

Even though they tend to be aggressive to other sharks, they are actually a pretty decent community fish. More information on good Rainbow Shark tank mates can be found further down in this guide.

Generally, the Ruby Shark will grow up to 6 inches and will usually live up to 8 years, although I have heard of them living even longer. The good thing about the Rainbow shark is that they are available all year round and cost as little as $3 a fish.

Getting Your Aquarium Right For Rainbow Sharks

Like with any fish, it’s important to get the fish tank set up right. You need to ensure they are not stressed, as this will make sure they not only get on with other fish better but they will also live longer. This section will go over what is needed to set-up the perfect environment for them.

The Tank

The Rainbow Shark is an active swimmer and an explorer, the tank should, therefore, be at least 50 gallons. A square aquarium is not recommended, they should have plenty of horizontal space. I would recommend getting a rectangle fish tank, as smaller ones do cause additional aggression and make them more territorial.

Even though they are bottom dwellers and spend a lot of their time down there, they are also able to jump out of the water. You want to, therefore, make sure a lid is on the tank and it is properly fastened.

It is important to keep the PH between 6-8 and even though it doesn’t have to be the same all the time, the PH should not change drastically as this can cause them to increase in aggression.

The temperature should be kept between 24-27 deg C (72-81 F) and the water should be changed on a weekly basis. As they are bottom dwellers, you should also clean the substrate often.


It is a good idea to try and replicate their natural habitat, they do prefer sandy bottoms. I would, therefore, recommend using fine grain sand on the bottom of your tank. It is also possible to use gravel but it should be fine if it has sharp edges it can causes cuts.


I would recommend looking into live plants for your Ruby Shark, this is because they do like to eat from them as well as algae. Plants are also excellent places for them to hide, which helps with their territorial nature.

As well as the plants, I would also recommend putting in some rocks, caves, driftwood and also ornaments that it can hide in.

NOTE: You can use fake plants but as they do like to nibble at them, I would recommend live plants.


As already mentioned the Rainbow Shark does require clean water, you will, therefore, want to renew the water on a weekly basis. You don’t need to clean in all but I’d recommend going for 25% of the water to be renewed per week. It’s also very important to use a siphon to clean the substrate.

The Ruby Shark is used to living in flowing water, to, therefore, help recreate its natural habitat I would recommend using a canister filter. These filters are a good choice as they help to introduce some water flow in the fish tank.

What Does The Rainbow Shark Eat?

When I did some research on feeding rainbow sharks I was initially confused as some websites would say they are herbivores, whereas others claim they are omnivores. Interestingly in the wild, the Rainbow shark does stick to a mainly plant-based diet, as well as consuming algae. They are however not the best algae eaters, so I wouldn’t rely on them for cleaning your tank…

Once added to a tank, they do tend to eat all types of foods. They are bottom dwellers so you need to feed them food that will drop to the bottom and not float along the top, often why they tend to eat leftovers from other fish in the tank.

I would personally recommend having their diet mostly consist of plant-based foods, it is this that helps give them a good coloring and provides them all the nutrients that they need. You could, however, complement this with some live food.

There is some excellent artificial food that will provide your Rainbow shark with everything they need. You should just make sure that it doesn’t float IE pellets are ideal and that it is high quality.

You want to feed them 2-3 times per day, ensuring they don’t eat too much. Remember they will eat other fishes leftovers so bear this in mind when feeding.

Rainbow Shark Food Summary

  • Omnivore (Herbivore in wild)
  • Diet should mostly be plant-based
  • Food should fall to the bottom of the take
  • Can compliment diet with live food
  • High-quality food is recommended for better health.

How To Determine Your Fish’s Gender?

Compared with some other fish, the Rainbow Shark is very hard to find its sex. This is because there are very few differences in gender, the main difference is when females have eggs and their abdomen becomes fat and rounded. Some males do have a little black on their anal glands. If you do have an albino one (although these are rare), you can usually tell better when breeding as the abdomen takes on a greenish tint.

The Rainbow Shark Breeding Guide

Breeding can be really exciting and rewarding, something that many beginners will want to try. Rainbow Sharks are however not the best fish to try and breed, mainly because they are so aggressive. Even the most experienced aquarists will not attempt to breed this fish.

There are no set of guidelines to breed this fish in an aquarium, most of them are bred commercial and then sent to stores to be sold. When they do mate the female will lay her eggs, it is then that the male fertilizes them.

Once the eggs are fertilised they will take a week in order for them to hatch.

Compatibility Guide – The Ideal Rainbow Shark Tank Mates

Since the Rainbow Shark is an aggressive fish, it’s very important to make sure you choose the right tank mates. This is because they are one of the most territorial freshwater fish, they typically dislike their own kinds.

It’s nice to see fish swim around together in a large group, the Rainbow Shark is however not going to do this as they are a very solitary fish. They do however make a great addition, with the vibrant red fins.

There have been cases in which people have been able to have more than one, although this is in very unique cases. You can have more than one, but you do need to have a much bigger fish tank.

Below are some really good examples of Rainbow Shark Tank Mates;

  • Danios
  • Barbs
  • Snails
  • Plecos
  • Rasboras
  • Gouramis
  • Clown Loach


Overall I do think the Rainbow Shark would make a great addition to your Aquarium, as long as they don’t have any additional sharks. If you are completely new to having your own fish tank then I would be tempted to wait until you have a little more experience but they are generally easy enough to look after if you have the right environment for them.

To reduce their stress, make sure the water is the right temperature and the PH is between 6.5-7.5. You want to make sure you have plenty of places for them to hide such as plants, rocks, bridges etc. Even though they are not actually a shark, I do think the look of the fins and the coloring would make them a great addition to any home aquarium.

I really hope this care guide on the Rainbow Shark has helped and answered your questions on feeding, breeding them and what tank makes would be most suitable. If you have any questions please put them in the comments below.

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