Rainbow Forktail Fish (Pseudomugil furcatus): Aquarium Care Guide

Rainbow Forktail Fish is one of the most underrated and beautiful freshwater fish in existence. We’re surprised so many aquarists don’t know about them!

These fish are peaceful, easy to care for and amazing to look at. In fact, they might be one of our favorites!

But due to its low popularity, many people do not know how to care for this species. This leads to unhappy and unhealthy fish.

Don’t worry though, this guide has you covered. She will teach you all the basics of Forktail Rainbow Fish care so she can buy some with confidence!

Species Summary

The Forktail Rainbowfish (Pseudomugil furcatus) is a lesser-known freshwater species that has a lot to offer.

Also known as the Blue Eye Forktail, it has a vibrant, colorful appearance that stands out against a natural background. Combine that with their various fin shapes and you have a fish that is sure to turn heads in your tank.

Geographically, the wild distribution of rainbow forktail fish is relatively small. They come from the rivers of the Milne Bay province of Papua New Guinea.

Fortunately, this species frequently breeds in captivity. Therefore, they are available in specialized breeders’ aquarium shops all over the world.

Playful by nature, Rainbow Forktails are known for creating a stunning display of color in a home aquarium. They are a joy to care for and are easy enough to breed even for novice fish enthusiasts.

Life expectancy

Even with superior care, the average lifespan of a forktail rainbowfish is around three years at most. In reality, this is not very long and often surprises potential owners.

In poor living conditions, their life expectancy is even shorter. Like any captive fish, Forktail Rainbowfish need high-quality water conditions and a good diet. Without good care, these fish will experience health complications and a short overall lifespan.


The Forktail Rainbowfish is one of the most visually unique fish in the trade. Despite its small size, there are many different physical details worth mentioning.

Let’s start with the shape.

The fish has a relatively simple torpedo-shaped body. The head is rounded and finished off by an upper mouth, which is oriented upwards.

The fins are what make the Forktail Rainbow shape different. The spiny dorsal fin is small and faint. However, it is accompanied by a larger soft dorsal fin. It is square and extends towards the caudal fin.

A similarly shaped anal fin is located on the lower part of the fish’s body. As for the pectoral fins, they are up. The fins create a wing-like effect that is very different from what you may be used to seeing with freshwater fish.

The Forktail Rainbowfish is also an extremely colorful fish. The main color of the body is silver-gray with a greenish tint. Bright yellow accents are found throughout the body.

You can find the color on the top and bottom of the fish, as well as on the edges of the fins. Subtle black stripes accompany the yellow. The final signature detail of the Forktail Rainbow Fish is its sparkling blue eyes!

Author’s Note: This species is sexually dimorphic. Males tend to be more vibrantly colored. The fins are generally longer as well. Females may lack the wing shape of the pectoral fins.

Average size

The average size of a Rainbow Forktail fish is only about two inches long. This is not very large at all, and even the largest specimens will top out at around 2.3 inches.

In our opinion, this small size really goes well with its color. When you see these tiny creatures swimming around it creates a very dazzling effect!

Rainbow Forktail Fish Care

If you are looking for a species of fish that is easy to keep, this freshwater fish is definitely worth considering. Part of the reason forktail rainbowfish care is so simple is the fact that this is a highly adaptable species that does well in a wide range of conditions.

In fact, they do very well in captivity and can even cohabit with many other species (more on that a bit later).

With that said, there are some care requirements you should be aware of. To help these fish reach their full potential in your tank, you will need to provide for their basic needs!

Here are some established care guidelines that you should follow.

tank size

At a minimum, Rainbow Forktails need a tank size of at least 20 gallons. This is suitable for a small group of fish.

Author’s Note: If you have the space, a 30-gallon tank is much better.

Some fish keepers make the mistake of thinking that these fish can be kept in small tanks because they are so small. However, there is a reason why a large aquarium is a must with Rainbow Forktail Fish.

These freshwater fish need a lot of room to swim. Not only that, but they are much happier and healthier when kept in groups.

Providing that extra space will allow you to keep a larger group together. Plus, it provides more open swimming space for fish to enjoy!

water parameters

The best way to keep Rainbow Forktails happy and healthy is to replicate their natural habitat in the wild. Its native waters are slow-moving and surrounded by vegetation.

The streams they call home are often surrounded by tall trees and plants. This has an effect on the quality of the water. It is best to mimic those conditions as closely as possible.

The good news is that the blue-eyed forktail rainbowfish is not a picky eater. It can be adjusted to many conditions. As long as you stay within the following acceptable parameter ranges, you should be fine.

  • Water temperature: 75°F to 79°F
  • pH level: Between 6.0 and 8.0 (around 7.6 is optimal)
  • Water hardness: 5 to 12 dKH

We recommend investing in a reliable thermometer to ensure your aquarium heater is accurate. Their water temperature window isn’t very big, so you have to get it right!

Setting up the interior of your tank

The decoration in your tank can help this fish thrive and make its vitality really stand out! They do best in natural settings that mimic wild currents.

Start with a dark colored substrate. Rainbow Forktails generally occupy the center of the tank, but a dark substrate and background can bring out their vivid coloration.

Next, add a variety of plants to the mix. These fish like feathered plants. Fine-leaved aquatic moss and densely rooted floating plants work well. You can try everything from Water Hycaninth to Java Moss.

Author’s Note: Plants act as shelter for fish. They also diffuse some light to make things more comfortable. You may also find your fish playing on the plants. They like to go in and out of plants for fun!

To complement the plants, incorporate some rock formations and driftwood. Just a few can make a little difference.

Your filtration system should be efficient enough to circulate the tank frequently and also help oxygenate the water. Forktail rainbowfish like a little movement in the water, but it can’t be too strong.

Lastly, there is the lid. Make sure you get a strong, secure lid! These fish are notorious for jumping out of the water to their death (something not many owners are prepared for).

Possible common diseases

The good news is that Forktail Rainbowfish are not affected by any species-specific ailments. But they can experience all the standard freshwater diseases. This includes Ich, parasites, bacterial infections, and fungal infections.

The most common disease that aquarists have to deal with is Ich. It is a contagious disease that breaks out when fish become stressed. Stress causes the immune system to weaken, allowing disease to take hold.

The same can be said for most freshwater diseases. The best thing you can do is keep the tank in good condition to avoid unnecessary stress for your fish. This means frequent cleaning, routine water checks, and regular water changes.

All of these maintenance tasks will help you keep ammonia and nitrate levels under control. It can also help you spot potential changes in your water before they cause a problem.

Food and Diet

Forktail rainbowfish are not picky eaters when it comes to food. They will eat almost anything and have no special requirements.

You can provide nutritionally balanced standard dry flakes as the stable of your diet. To supplement that, provide live or frozen food snacks. You can offer brine shrimp, cyclops and daphnia.

Author’s Note: Only feed as much as the fish can eat in about two minutes. Avoid overfeeding to preserve water conditions as well (too much extra food in the water can lead to serious problems).

behavior and temperament

These fish are very peaceful and playful. They get along very well with most other peaceful species.

The only time you will encounter aggressive behavior is around breeding time. The males often put on a show and do some training. Don’t worry though, this behavior is quite innocent and usually doesn’t cause injury!

Forktail Blue Eye Rainbowfish can also have some problems with slow moving fish that have long tails. They are notorious fin nippers, so it’s best to keep those types of fish out of the tank.

Forktail Rainbowfish are calm and will spend most of the day swimming around the tank in groups. They are agile swimmers, so don’t be surprised if you see the fish jumping from one end of the tank to the other!

Forktail Rainbowfish Tank Mates

As we mentioned earlier, these fish do best in groups. It is important to keep at least six fish together. If you have a larger aquarium, aim for at least ten fish!

Staying in a group will help the fish feel safe and confident. The solitary forktail rainbowfish will spend most of its time hiding. They may even lose their color.

To keep male-to-male aggression to a minimum, try to keep more females. There must be at least one female for every male. If possible, make two females for every male.

In addition to fish of the same species, Forktail Rainbowfish can cohabitate with other calm tankmates. They do well with fish that occupy other parts of the water column.

Keep things quiet and avoid any big fish that might eat the Rainbow Forktail Fish for lunch!

Here are some good tankmates for Forktail Rainbowfish:

  • Celestial Pearl Danio (other Danios are good too)
  • rasbora chili
  • Small gobies (such as the bumblebee)
  • Harlequin Rasbora
  • Various types of tetras (Ember, Serpae, Neon and Emperor are our favorites)
  • apistogram
  • dwarf gourami
  • Peaceful bottom-feeding fish


Forktail rainbowfish are quick to start breeding in captivity. Due to their shorter lifespans, most are ready to spawn when they are around eight months old.

Reproduction is a bit different for this species. To increase the chances of survival of the fry, create a separate tank for the eggs. Be sure to match breeding tank conditions to avoid shock issues.

These fish can breed in their main tank, but you can also create a separate breeding tank. Either way, make sure there is plenty of dense vegetation. Use feathered plants or spawning mops. Arrange them around the edges of the tank.

The males will claim one of the plants in the corner while the females stay in the center. At dawn, the males will put on a show for the females. Eventually she will follow the males back to her plant and begin to reproduce.

Author’s Note: Forktail rainbowfish are continuous spawners. They lay small batches of eggs over several days or weeks. You need to keep an eye on the eggs and move them to a separate tank. The adults will try to eat the eggs if they get the chance.

As the female continues to lay batches of eggs, the individual eggs will get smaller and smaller until she is finished.

The eggs take a while to hatch. Depending on water conditions, they could hatch for up to 21 days! The good news is that the fry are free-swimming immediately after hatching. It can go directly to brine shrimp or infusoria.

Feed them several times during the day. Also, change 20 percent of the water each week to keep the tank in good condition as the fry become adults.


As you can see, forktail rainbowfish care is quite easy. These fish require very little maintenance, making them perfect for aquarists of any experience level.

Owning these beautiful and unassuming fish is something all aquarists should experience at some point. It is a combination that you do not find with many other species!

If you have any other questions about the Blue-Eyed Forktail Rainbowfish, we’d be happy to help. Simply contact us through the website and we’ll get back to you as best we can.

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