Forktail Rainbowfish (Pseudomugil furcatus): Ultimate Care Guide


With eye catching shoaling behavior, Forktail Rainbowfish are a great addition to the medium or large aquarium. Native to parts of Papua New Guinea, this species appreciates environments that include clear, slow moving water with ample plant growth.

These fish need a larger aquarium than their size suggests. Though they only grow to a length of about 2 inches, they are happiest in groups of 8 – 10 or more, and they appreciate lots of swimming space.

Forktail Rainbowfish Care

Planning on adding Forktail Rainbowfish to your tank? This guide will help you get excellent results from this great species!

Forktail Rainbowfish Temperature

Water temperature between 75°F and 79°F (24°C to 26°C) is the ideal for Forktail Rainbowfish. To increase the chances of spawning, raise water temperature to 83°F.

Forktail Rainbowfish Water pH

Forktail Rainbowfish can tolerate a range of water pH between 6.5-8.0. This wide selection increases the available choice of tank mates.

Forktail Rainbowfish
Forktail Rainbowfish (Pseudomugil furcatus)

Forktail Rainbowfish Size

The average size of a mature Forktail Rainbowfish is around 2 inches. They generally won’t grow beyond 2.4 inches even with expert care.

Forktail Rainbowfish Food & Diet

Forktail Rainbowfish aren’t finicky eaters and have almost no special food requirements. Regular tropical flake food can be their staple diet. When spawning is desired, or as a special treat, introduce live foods.

Forktail Rainbowfish Lifespan

Forktail Rainbowfish don’t have a long lifespan. Even with excellent care they will only live around 3 years. If you want to keep this species in your aquarium over the long term, consider allowing them to breed.

Forktail Rainbowfish Tank Size

Although the average size of a single Forktail Rainbowfish is about 2 inches, they prefer to live in groups of 8 – 10 or more. An aquarium of around 30 gallons will give them enough room to swim.

Your Forktails enjoy lots of plants and driftwood to hide and spawn in. This will take up a fair amount of room in your aquarium so plan accordingly.

Forktail Rainbowfish Tank Setup

A covered tank with ample plants and a dark substrate can form a good environment for your Forktail Rainbowfish. Though beautiful, this species is light colored and choosing dark gravels and background can showcase their natural beauty. This species is known to jump so proper aquarium covering is necessary.

Choose enough large background plants to contrast with your fish and fill in the rear portion of the tank. Forktail Rainbowfish swim in mid levels and need a backdrop that rises high enough, and is dark enough to provide contrast. Duckweed and floating plants like Hornwort, with ample root systems are good choices. Forktails won’t disturb most plants so you have a large range of choices.

In addition to plants you’ll want enough hardscaping material to give your Forktail Rainbowfish cover and hiding spots. Driftwood and bark are the most popular but rocks are also acceptable. Plants like Anubias, Java Fern and Java moss don’t need to be planted in substrate but can be anchored directly to your hardscape. These plants let you add variety to you hardscape material and allow crafting lush and stunning aquarium environments.

Filtration is important for Forktail Rainbowfish. Not just for water quality, but providing movement. Your Forktails are happiest with gentle movement in their water. You will want a filtration system that can cycle the water in your aquarium at least 5 times an hour. For a 30 gallon tank you’ll want a filter that moves 150 to 200 GPH (Gallons Per Hour). This should keep your water clean and provide enough current to please your Forktails.

Forktail Rainbowfish are often seen in densely planted aquariums. This is a popular layout and it looks great. However, heavily planted tanks can often struggle due to lack of sufficient Co2. While your fish produce some Co2, it probably won’t supply a tank with lots of plant material.

Consider are injected Co2 systems. These take gas from compressed cylinders and add it slowly to the water in your tank. They have to be monitored and adjusted to ensure that tank levels don’t rise enough to suffocate your fish. Injected Co2 systems increase plant growth and inhibit algae formation. These systems aren’t required for planted tanks and may not be a good fit for your aquarium’s style.

Forktail Rainbowfish Breeding

Forktail Rainbowfish breed easily and are ready to spawn when they are 8 months old. One suggested breeding setup is to place one male and two females in a bare 5 gallon tank with purchased or homemade spawning mops. A spawning mop resembles a cluster of green plant material and is made with wool or artificial fiber yarn. Your breeding tank should also be equipped with a sponge filter and heater. The temperature should be set higher than normal–up to 83°F–to encourage spawning.

A male will chase females into the mop where they will lay and fertilize eggs. This behavior takes place over an approximately three week period. After this you can remove the fish and let the eggs hatch. Due to the long egg laying period, fry will continue to hatch for around three weeks. These fry can be fed immediately with live brine shrimp. Feed brine shrimp until the fry are about 6 to 8 weeks old. After this you can add in other foods–like crushed flake–while continuing with brine shrimp until they are comfortable with regular flake food.

Forktail Rainbowfish Male vs Female

Male Forktail Rainbowfish can be distinguished by their sharper colors and more pronounced fins. Examining a single specimen makes this task difficult. Inspect a few Forktails to make picking out this difference easier.

Forktail Rainbowfish Disease

Forktail Rainbowfish are susceptible to the same diseases as other freshwater fishes. However, there are no species specific diseases to watch for. The rules to keep your Forktails healthy are the same as most other freshwater fish: give them quality food and monitor their water conditions and temperature.

Forktail Rainbowfish Tank Mates

Usually mild mannered, Forktail Rainbowfish will integrate well in a community tank. Male Forktails can often fight other males. Keep this behavior to a minimum by keeping more females than males; a ratio of 2 to 1 is recommended.

Your Forktails will want company and enjoy shoaling with their own kind. Plan to keep at least 8 to 10 together in a tank.

Forktails will integrate well with tetras, dwarf cichlids, danios, rasboras or other fish of similar size. It’s best to avoid larger fish that might see your Forktails as food–a particular problem when they are juveniles.

Where can I find Forktail Rainbowfish for sale?

Forktail Rainbowfish are available from a number of sellers on the Internet. Often you can purchase Forktails in schools of 6 or 12. Prices range from $6 US for a single to just over $40 US for a school of 12.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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