Rainbowfish Care And Interesting Facts [The Complete Guide]

Rainbowfish Care And Interesting Facts [The Complete Guide]

Rainbowfish in an aquarium

Rainbowfish are extremely popular for their colorful appearance, peaceful behavior, and friendly nature.

They’re an ideal choice for both seasoned and beginner aquarists alike.

Let’s learn more about these beautiful fish in more detail.

Rainbowfish Species Overview

Rainbowfish are small, colorful freshwater fish that belong to the Melanotaeniidae family.

They inhabit the freshwaters of Australia, Madagascar, Indonesia, and New Guinea.

Most species of rainbowfish are schooling fish. So you must keep them in schools of 6 or more.

These fish must be kept in a healthy environment with live aquatic plants and live food to eat.

Rainbowfish can be found in various habitats, including rivers, lakes, swamps, and backwaters.

Most of the rainbowfish species used in the aquarium trade are captive bred.

These fish are an excellent choice to diversify your aquarium and add some beautiful colors.

Using a dark-color substrate can help intensify the natural color of rainbowfish.


Beautiful rainbowfish

Rainbowfish come in a variety of colors, depending on their species.

Most rainbowfish have silver or blue-green bodies with pink bellies and clear or red-orange fins.

Rainbowfish aren’t brightly colored when they hatch from eggs. They’re plain silver-white.

As they mature, their color becomes more pronounced. The male fish starts to look more colorful than the female.

Rainbowfish have two dorsal fins and gain their beautiful colors as they grow.

In some rainbowfish species, male fish have longer and more pointed fins than female fish.

Rainbowfish usually have laterally compressed bodies that resemble an elongated diamond shape.

Males are brighter than females and develop a courtship stripe when they spawn.

Names of Species

There are around 50 documented species of rainbowfish in the world.

Due to their increasing popularity, many of them are now part of the aquarium trade.

Rainbowfish are generally classified by their body coloration or place of origin.

CountryRainbowfish Species
AustraliaBanded Rainbowfish, Black-banded Rainbowfish, Cairns Rainbowfish, Chequered Rainbowfish, Desert Rainbowfish, Eastern Rainbowfish, Exquisite Rainbowfish, Lake Eacham Rainbowfish, MacCulloch’s Rainbowfish, Murray River Rainbowfish, Ornate Rainbowfish, Pygmy Rainbowfish, Slender Rainbowfish, Threadfin Rainbowfish, Western Rainbowfish
IndonesiaAyamaru Rainbowfish, Boeseman’s Rainbowfish, Celebes Rainbowfish, Misool Rainbowfish, Waigeo Rainbowfish
MadagascarMadagascar Rainbowfish
New GuineaArfak Rainbowfish, Angfa Rainbowfish, Axelrods Rainbowfish, Barred Rainbowfish, Bleher’s Rainbowfish, Bulolo Rainbowfish, Corona Rainbowfish, Dwarf Neon Rainbowfish, Fly River Rainbowfish, Goldie River Rainbowfish, Highlands Rainbowfish, Irian Jaya Rainbowfish, Lake Kutubu Rainbowfish, Lake Kurumoi Rainbowfish, Lake Tebera Rainbowfish, Lake Wanamaker Rainbowfish, Lorentz’s Rainbowfish, Mayland’s Rainbowfish, McCulloch’s Rainbowfish, Mountain Rainbowfish, Northern Rainbowfish, Ogilby’s Rainbowfish, Oktedi Rainbowfish, Parkinson’s Rainbowfish, Pima River Rainbowfish, Ramu Rainbowfish, Red Rainbowfish, Red Striped Rainbowfish, Sentani Rainbowfish, Sepik Rainbowfish, Serong Rainbowfish, Silver Rainbowfish, Spotted Rainbowfish, Strickland Rainbowfish, Tami River Rainbowfish, Van Huern’s Rainbowfish, Yapen Rainbowfish


Rainbowfish live for varying lengths of time. Most rainbowfish species have an average lifespan of 5 to 8 years.

However, the Madagascar rainbowfish can live up to 11 years.

Large rainbowfish live longer than small rainbowfish.

Some popular species like the threadfin, celebes, and forktail have short life expectancies, under five years.

On the other hand, a well-maintained aquarium can help boost the life span of rainbowfish.

In captivity, they can live between five to ten years.

By providing a healthy environment, a well-balanced nutritious diet, and pristine water conditions, you can improve the overall health and longevity of rainbowfish.

Average Size

The average size of an adult rainbowfish is between 3 to 6 inches in length, depending on the species.

Male rainbowfish are usually longer than the normally plump female rainbowfish.

The neon dwarf rainbowfish is the smallest rainbowfish with an average size shorter than 3 inches in length.

On the other hand, the largest known rainbow fish is Van Heurn’s rainbowfish, which grows up to 7.9 inches in length.

Rainbowfish Tank Setup

Rainbowfish in a tank

Rainbowfish do well in aquariums that mimic their natural habitat.

So it’s essential to replicate the water conditions of their natural environment in the tank to make them feel safe and happy.

Let’s now understand how to set up a rainbowfish tank in detail.

Tank Size

Rainbowfish are active swimmers and need adequate swimming space.

So you should use a 15-gallon elongated tank to accommodate up to six or more small rainbows.

Rainbowfish species larger than 3 inches must be kept in at least a 30-gallon tank.

Increase the tank size by 2 gallons for each additional small rainbowfish and 5 gallons for large rainbowfish.

A large tank can also easily accommodate live aquatic plants and aquarium equipment.

So you can efficiently re-create their natural habitat inside the tank.

Tank Equipment And Decorations

Rainbowfish need tanks with open spaces to swim as these fish are active swimmers.

A well-maintained tank with dense vegetation, rocks, and caves will also provide rainbowfish with the required hiding spot throughout the tank.

Rainbowfish prefer hard, alkaline water. So choose aquatic plants that can tolerate this type of water.

You can also create some artificial lighting to imitate natural sunlight.

Rainbowfish are known to jump out of their tanks. So you need to cover their tank with a lid.

Given below are the items required in a rainbowfish tank:

  • A dark substrate with a mix of sand and gravel,
  • Filter,
  • Heater,
  • Live plants like Anubias, Duckweed, Glosso, Java Fern, Sagataria, Stargrass, Rotala, Wisteria, etc.,
  • Powerheads for water movement,
  • Aquarium Lights,
  • Decorations like artificial rocks, caves, etc.

A thoughtfully replicated natural environment will help the rainbowfish de-stress, remain happy, and be a great addition to any room of your house.

Rainbowfish Care

Rainbowfish taken well care of

Rainbowfish are hardy fish that need adequate care for healthy development.

They need a well-balanced diet, clean water, and stable water parameters.


Rainbowfish are omnivorous fish that need a balanced diet of plant and animal matter for optimal growth.

They primarily eat food that floats on the water’s surface, including floating vegetation, insects, small crustaceans, mosquito larvae, and zooplankton in the wild.

Many aquarists feed their rainbowfish high-quality flakes and pellets containing both vegetable and meat content in their daily diet.

You can also feed live food two to three times a week. Live food has a high nutritional value and helps to enhance the fish color.

Some of the live food that you must feed your rainbowfish are:

  • Bloodworms,
  • Brine shrimp,
  • Mosquito larvae,
  • Small insects, etc.

Rainbowfish are surface feeders and must be fed what they can consume within three minutes.

Avoid sinking food and remove leftovers to avoid waste buildup.

Water Parameters

Rainbowfish are usually raised in alkaline waters, but commercially bred fish can tolerate varying levels of water conditions.

Water temperature, pH level, and water hardness are critical parameters.

The ideal water parameters to keep rainbowfish healthy are:

Water Temperature74°F to 80°F (23°C to 27°C)
Water pH6.5 to 8.0
Water Hardness (dGH)9 to 20

Tank Maintenance

Regular water change and tank maintenance ensure stable water conditions for the overall well-being of rainbowfish.

So regular partial water change between 25% to 30% will keep the water clean with stable water parameters.

In contrast, poor water conditions will make the rainbowfish weak and stressed.

Some signs of sickness include dull coloration, erratic swimming patterns, and loss of appetite.

Test the water regularly to avoid the buildup of ammonia or nitrates.

It’s also best to use a heater to maintain a stable temperature.

Common Diseases

Rainbowfish are hardy but aren’t entirely immune. Irregular tank maintenance and water change can result in a toxic buildup.

To prevent diseases, ensure that water parameters remain stable.

Some of the common rainbowfish diseases are:

  • Fin Rot,
  • Ich,
  • Fungus,
  • Velvet,
  • Dropsy,
  • Protozoan, and
  • Cottonmouth or columnaris.

To avoid fungal and bacterial infections, always quarantine the new rainbowfish for two weeks before adding them to the tank, help them to de-stress, and feed them with a nutrient-rich diet.

Rainbowfish Behavior And Temperament

Most rainbowfish species are colorful, peaceful, social, and thrive in schools of six or more.

They can brighten up the aquarium with their unique colors and are great for community fish tanks.

However, rainbowfish aren’t always peaceful.

There are times when these fish display aggression toward each other or other tankmates.

Rainbowfish can get aggressive while feeding or when kept in a constrained environment.

The male rainbowfish can also become territorial and fight with other males during the mating season.

Rainbowfish Tankmates

Rainbowfish tankmates

Rainbowfish get along with their kind and do better when kept in schools of six or more.

You can keep different species of rainbowfish together if they’re similar in size.

A ratio of three females to two males reduces aggression.

Since rainbowfish are docile, hardy, and colorful, they should be housed in community tanks with equally docile and friendly fish species.

Rainbowfish live in the middle and upper levels of the tank, so they usually won’t cause problems for bottom-dwelling fish.

However, choose bottom-dwellers that are similar in size and temperament.

Some of the popular compatible tankmates for rainbowfish are:

  • Danios,
  • Barbs,
  • Corydoras catfish,
  • Caridina shrimp and other fully grown adult shrimp,
  • Guppies,
  • Kribensis cichlid,
  • Mollies,
  • Otocinclus,
  • Rasboras (peaceful species),
  • Tetras,
  • Neocaridina, and
  • Snails.

Rainbowfish are compatible with fish species similar in size and temperament.

But it’s best to avoid some fish species that can be aggressive and bully the docile rainbowfish.

Fish species that you can’t keep with rainbowfish are:

  • Bettas, and
  • Cichlids.

Rainbowfish Breeding

Rainbowfish species are easy to breed, but a separate breeding tank is recommended to increase the survival of their fry.

Rainbowfish species vary in their preference for spawning. Some prefer to spawn in pairs, while others in groups.

Keep the following tips in mind when breeding rainbowfish:

  • Create a shallow, 5 to 10-gallon tank for breeding. A water temperature of 77°F to 80°F and a pH of 7.5 are best for most rainbowfish species. Gradually raise the water temperature by a few degrees.
  • Feed rainbowfish pairs with live food to provide high nutrition.
  • Add java moss and spawning mops to the bottom of the tank to catch the eggs.
  • Male rainbowfish gaining more coloration and swimming rapidly in front of the females indicates courting behavior.
  • Female rainbowfish become fat when they’re ready for spawning.
  • Rainbowfish spawn during the evening or early morning. Females deposit between 5 to 30 eggs per batch.
  • Once the breeding process is complete, remove the parents from the tank so that they don’t eat any of the eggs.
  • Feed newly hatched fry with infusoria for about a week. After a week, you can move the fry onto newly-hatched brine shrimp.

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