Eastern rainbowfish Care Guide: Diet, Tank Mates, Diseases, Breeding & More

Updated: December 17, 2022

The Eastern rainbowfish is a stunning freshwater fish that is native to Australia.

This fish is relatively easy to care for and is a great addition to any freshwater aquarium. They are a peaceful fish that gets along well with other tank mates.

The Eastern rainbowfish is a great beginner fish and is a good choice for anyone looking to add some color to their aquarium.

Species overview

The Eastern rainbowfish (Melanotaenia splendida splendida) is a freshwater fish that’s found in a very specific area of Australia.

They are located along the coast of Queensland in the Mary and Burnett River systems.

This species of rainbowfish is very peaceful and can be kept with a wide variety of other fish. They are a popular choice for community tanks.

One of the most notable things about the Eastern rainbowfish is their bright colors. They are mostly blue with a yellowish-orange belly. This coloration is what makes them so popular among aquarium enthusiasts.


Eastern rainbowfish

The Eastern rainbowfish is an absolutely beautiful freshwater fish that is sure to brighten up any aquarium.

These fish are mostly blue in color with a few orange and red accents. The blue coloration can range from a light sky blue to a deep navy.

The fins on these fish are also very colorful. The dorsal fin is usually blue with an orange or red stripe running down the middle. The anal and pectoral fins are usually orange or red. The caudal fin is forked and blue with an orange or red stripe running down the middle.

The Eastern rainbowfish is a relatively small fish, only growing to be about 4 inches in length.


The average lifespan of Eastern rainbowfish is around 4 years. However, there have been reports of some fish living for up to 8 years in captivity.

As with any other fish, their lifespan will be determined by a number of factors such as the quality of their environment, their diet, and whether or not they have any underlying health conditions.


The Eastern rainbowfish is a relatively small fish, only growing to be about 4 inches in length.


Tank Size

The minimum tank size for Eastern rainbowfish is 20 gallons. If you plan on keeping a group of these fish together, you’ll need to increase the size of your tank accordingly.

For every extra fish you add to your tank, you should add 2-4 gallons. This means that if you want to keep a school of 5 rainbowfish, you’ll need a minimum of a 30 gallon tank.

Water Parameters

The Eastern Rainbowfish is a freshwater fish that is found in the rivers and streams of Northern Australia and New Guinea. In the wild, they prefer slow-moving waters with plenty of vegetation.

To replicate this in the home aquarium, you need to maintain certain water parameters. The most important factors are temperature and pH. The ideal temperature range for Eastern Rainbowfish is 75 to 82 degrees Fahrenheit. The pH should be between 6.5 and 7.5.

Water hardness is not as critical, but the general range for this fish is 5 to 15 dGH. Alkalinity levels should be between 4 and 8 dKH.

What To Put In Their Tank

When it comes to setting up the interior of an aquarium for Eastern rainbowfish you can be as creative as you want. There aren’t any specific things that this species NEEDS to have, which gives you plenty of options.

We recommend some of the standard decorations that you find in a lot of freshwater tanks. There are a ton of great plants you can include (like hornwort or water wisteria). You can even throw in some floating aquarium plants too!

Rocks, driftwood, and caves are all suitable as well. It’s important to avoid going overboard with this since these fish like some room to swim.

Also, if you’re keeping your Eastern rainbowfish in a smaller tank then it’s going to be difficult to include a lot of this stuff anyway.

A classic gravel substrate is always a good choice, but you can do with something soft and sandy if needed too (use other species you keep as a guide with this).

Common Diseases

Eastern rainbowfish are a pretty hardy species, but they’re not immune to disease. The most common illness that these fish suffer from is ich.

This is a parasite that can quickly spread through an entire tank and is pretty difficult to get rid of. The most obvious symptom of ich is the presence of white spots on the body of your fish.

If you notice this, it’s important to take quick action. There are a few different treatments for ich, but the most effective one is to raise the temperature of the water in your tank.

This will speed up the life cycle of the parasite and make it easier to get rid of. Just be sure to slowly acclimate your fish to the new temperature so they don’t experience any stress.

Another disease that these fish are prone to is fin rot. This is usually the result of a bacterial infection and can be pretty serious if it’s not treated quickly.

The most obvious symptom of fin rot is, you guessed it, the rotting of the fins. This can happen relatively quickly, so it’s important to keep an eye out for any changes in your fish’s appearance.

If you notice any changes, the best course of action is to consult a vet or experienced fish keeper. They’ll be able to recommend the best course of treatment.

Behavior & Temperament

The Eastern rainbowfish is a peaceful and social creature that does best in a community tank. It’s important to note that these fish need to be in groups of at least six. Otherwise, they may become stressed and their colors will fade.

When they’re in a group, they tend to swim in formation and play around a lot. They’re very active fish and are constantly on the move. They’re also known to be jumpers, so it’s important to have a tight-fitting lid on your tank.

As for their temperament, Eastern rainbowfish are relatively calm fish. They’re not aggressive and usually leave other fish alone. The only time you may see them become aggressive is during spawning season. Otherwise, they’re pretty peaceful.

Tank Mates

Eastern rainbowfish are a great addition to any freshwater community tank. They’re peaceful, brightly colored, and easy to care for.

Not only that, but they’re also compatible with a wide range of other fish species. This makes them a great choice for beginners and experienced aquarium hobbyists alike.

When choosing tank mates for Eastern rainbowfish, it’s important to consider the size of your fish. These fish can grow up to 4 inches (10 cm) in length, so they need plenty of space.

You’ll also want to avoid any fish that are too aggressive. Eastern rainbowfish are peaceful by nature and don’t do well with bullies.

With that in mind, here are some excellent Eastern rainbowfish tank mates:

  • Guppies
  • Platies
  • Mollies
  • Swordtails
  • Neon Tetras
  • Ember Tetras
  • Cardinal Tetras
  • Black Skirt Tetras
  • Silver Dollar Fish


Eastern rainbowfish are a little bit more difficult to breed than some of the other fish on this list. They’re picky about their water quality and they don’t do well in crowded tanks.

That said, it is possible to breed them in captivity. It just takes a bit of work.

The first step is to set up a breeding tank. It should hold at least 20 gallons of water and have a sandy bottom. Add some plants and hiding places, but don’t make it too crowded.

Next, you need to adjust the water quality. The temperature should be between 73 and 82 degrees Fahrenheit. The pH should be between 6.5 and 7.5. And the hardness should be between 5 and 15 dH.

Once the tank is set up, add two males and four females. It’s best to add the males first so they can claim their territories.

Feed the fish high-quality foods and remove any uneaten food. Keep an eye on the water quality and do regular water changes.

When the females are ready to spawn, they will lay their eggs on plants or other surfaces in the tank. The males will then fertilize them.

After about two weeks, the eggs will hatch. Remove the adults from the tank and begin feeding the fry live foods.

As they grow, you can transition them to flake food. They should be ready to move to a regular tank after about four months.


Eastern Rainbowfish are a great addition to any freshwater tank. They’re relatively easy to care for, are very peaceful, and their bright colors add a lot of visual interest to your tank.

If you’re looking for a fish that is low-maintenance and will add some beauty to your aquarium, the Eastern Rainbowfish is a great choice!