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

Updated: November 23, 2022

The Lake Kutubu rainbowfish is a beautiful and peaceful freshwater fish that is perfect for community tanks. They are relatively easy to care for and are a great addition to any home aquarium.

Despite their peaceful nature, Lake Kutubu rainbowfish are relatively unknown in the fishkeeping world. This is likely due to their limited availability.

But if you’re lucky enough to find them, we think you’ll be very happy with this addition to your tank!

In this guide, we’ll teach you everything you need to know about Lake Kutubu rainbowfish care.

Species overview

The Lake Kutubu rainbowfish (Melanotaenia kutubuensis) is a species of freshwater fish that is endemic to Lake Kutubu in Papua New Guinea.

These fish are relatively small, only reaching a maximum length of about 3.5 cm. They are silver in color with a horizontal stripe of blue that extends from the gill cover to the base of the tail fin. The fins are also tinged with blue.

Lake Kutubu rainbowfish are peaceful fish that do well in community tanks. They prefer to school with other fish of their own species but can also get along with other peaceful fish.

These fish are omnivorous and will eat a variety of foods, including flakes, pellets, freeze-dried foods, and live foods.


Lake Kutubu rainbowfish

The first thing you’ll notice about this fish is their long and thin body shape. They have a torpedo-like build that tapers off at the end.

The body of the Lake Kutubu rainbowfish is a deep blue color. This coloration is solid all over their body with a few lighter blue stripes running horizontally along their sides.

The fins on this fish are all relatively the same size. The dorsal fin is located towards the back of the body and is slightly taller than the anal fin. Both of these fins are pointed at the end.

The caudal fin is forked and also pointed. Lake Kutubu rainbowfish have thin and delicate pectoral fins as well as small ventral fins.


Lake Kutubu rainbowfish have an average lifespan of 5 to 8 years. However, some individual fish have been known to live up to 10 years in captivity.

As with any other fish, there are a number of factors that can impact their lifespan. Things like water quality, diet, and stress levels can all play a role in how long your fish will live.


The maximum size of the Lake Kutubu rainbowfish is around 4 inches.


Tank Size

The minimum recommended tank size for Lake Kutubu rainbowfish is 10 gallons. If you’re looking for a freshwater fish that can fit in an average-sized tank, this is a good option.

Water Parameters

The Lake Kutubu rainbowfish is a beautiful fish that’s perfect for the intermediate aquarium keeper. These fish are not as delicate as some of the other rainbowfish, but they do require specific water parameters to stay healthy.

Here are a few tips to help you create the perfect environment for your Lake Kutubu rainbowfish.

  • Water Temperature: 72 to 82 degrees Fahrenheit
  • pH Levels: 6.8 to 7.6
  • Water Hardness: 4 to 10 dGH
  • Alkalinity Levels: 3-8 dKH

What To Put In Their Tank

The Lake Kutubu rainbowfish is a beautiful freshwater fish that’s native to Papua New Guinea.

They’re not too difficult to care for, but there are some things you’ll need to do to make sure they’re comfortable in their new home.

One of the most important things is to make sure their tank has plenty of hiding spots. These fish are skittish by nature and will appreciate some places to retreat to when they get scared.

Driftwood, rocks, and caves are all great options. Just make sure whatever you use is safe for the fish and won’t fall and crush them.

The substrate in their tank is also important. Lake Kutubu rainbowfish come from slow-moving streams and rivers with soft, sandy bottoms. You’ll want to replicate this in their aquarium as best you can.

Finally, you’ll need to make sure there’s plenty of vegetation in their tank. These fish love to hide among the plants and will feel much more comfortable with some cover.

Common Diseases

Lake Kutubu rainbowfish are quite resilient to disease and sickness. This is likely due to the fact that they come from such a remote and isolated location.

With that being said, they’re not invincible. They can still get sick if the conditions in their tank are not ideal or if they come into contact with a sick fish.

The most common disease that these fish experience is ich. This is a very common freshwater parasite that can affect any fish, no matter how big or small.

The most obvious symptom of ich is the presence of white spots on the body, fins, and gills of your fish. If you notice this, it’s important to act fast and begin treatment immediately.

There are plenty of other potential diseases that your Lake Kutubu rainbowfish could experience, but they’re not as common. Some other things to look out for include infections, parasites, and poor water quality.

As with any fish, the best way to prevent disease is by maintaining a clean and stable tank. This will create an environment that is less conducive to illness and will help your fish stay healthy and happy.

Behavior & Temperament

The Lake Kutubu rainbowfish is a peaceful and shy fish that does best in a community tank. They are timid fish that will often hide when they first introduced to a new tank.

It is best to keep them in a tank with other peaceful fish that share a similar water temperature, pH, and hardness. They are not known to be aggressive but may nip at the fins of other fish if they are feeling stressed.

The Lake Kutubu rainbowfish is a schooling fish so it is best to keep them in groups of 5 or more. They are known to be shy so the more fish there are in the school, the less likely they are to be stressed.

They are not known to be finicky eaters and will eat most aquarium foods. They prefer live and frozen foods but will also eat pellets and flakes.

Tank Mates

Lake Kutubu rainbowfish are a relatively peaceful species. They’re not known to be aggressive or territorial.

For the most part, they’ll stick to their own business and leave other fish alone.

Because of their peaceful nature, there are plenty of tank mates that work well with Lake Kutubu rainbowfish.

To help get you started, here are some compatible tank mates that tend to work well:

  • Tetras
  • Guppies
  • Mollies
  • Platies
  • Swordtails
  • Rainbows



Lake Kutubu rainbowfish are easy to breed in the home aquarium. They are mouthbrooders, which means the female will carry the eggs in her mouth until they hatch.

To start the breeding process, you will need to set up a separate breeding tank. The tank should be at least 20 gallons and have plenty of hiding places. Make sure the water is clean and the temperature is between 76 and 82 degrees Fahrenheit.

When ready, add two females for every male. The fish will start to pair off and mate. After spawning, the female will mouthbrood the eggs for about three weeks.

During that time, she won’t eat. So, it’s important to remove her from the breeding tank once the eggs have hatched. The fry can then be fed baby brine shrimp and other small foods.


The Lake Kutubu rainbowfish is a beautiful and unique fish that is perfect for the beginner aquarist. They are very easy to care for and will do well in a community tank.

They are also a great fish for breeding, so if you’re looking to get into that aspect of the hobby, this is a great fish to start with.

Overall, we think the Lake Kutubu rainbowfish is a great option for anyone looking for a new and exciting fish for their tank.