Rainbowfish: Species Profile

Category: Rainbowfish

Common Names: Australian Rainbowfish

Scientific Name: Melanotaenia fluviatilis

Family: Melanotaeniidae

Minimum Tank Size: 55 Gallons

Care Level: Easy

Temperament: Peaceful

Max Size: 4 Inches

Temperature: 72-76 F

pH: 7.0-8.0

Tank Level: All

Colors: Silver

Diet: Omnivore

Breeding: Moderate

Rainbowfish with Large Rock

Rainbowfish Species Overview

The rainbow fish, scientific name melanotaeniidae, live in:

  • Northern and eastern Australia
  • New Guinea
  • Cenderawasih Bay
  • Raja Ampat Islands
  • Sulawesi
  • Madagascar

Rainbowfish are gregarious; they play well with almost every other fish species.

The fish are freshwater dwellers residing in rivers, lakes, and swamps.

Rainbow fish lay eggs to reproduce and prefer to move in small schools.

Rainbowfish have six genera.

There are 60 known species of rainbowfish, the most popular of which are:

Boesemani Rainbowfish

The boesemani rainbowfish, whose scientific name is Melanotaenia boesemani, is one of the most widely recognized varieties of the species. Boeseman make excellent pets, thriving in aquariums. The two-toned fish enjoy community and get along well with other species.

Boesemani are identifiable by their bright colors: they have bluish purple heads and orangish red bodies. Male boesemani get brighter when they’re ready to breed.

Axelrod Rainbowfish

Chilatherina axelrodi, or the axelrod rainbowfish, are light-pastel colored. The fish are iridescent blue, with a horizontal black line along their abdomens. The axelrod fish gravitate towards waters similar to their natural habitats in Papua New Guinea. These streams move gently and slowly, creating a calm atmosphere for the creatures.

Desert Rainbowfish

Melanotaenia splendida tatei are also called desert rainbowfish. These lightly colored swimmers call Australia home. The desert rainbowfish are lighter colored. The males are white with green or purple tinted fins. The females are also white; however, they have a silvery tint. Desert rainbowfish are higher maintenance than other breeds, with more stringent water needs.

Madagascan Rainbowfish

The magagascan rainbowfish, scientifically named Bedotia madagascarensis, is silver and yellow. The male swimmers bear brighter, more concentrated colors than the females. The fish are slim, and while they live longer lives than many of their brethren, they also have very particular water needs.

Banded Rainbowfish

Themelanotaenia trifasciata, or branded rainbowfish, are strikingly beautiful. Their bright colors and pleasant demeanors endear them to aquarium owners. The swimmers enjoy community and get along well with other fish. The males can become aggressive during mating season.

Threadfin Rainbowfish

The threadfin rainbowfish, or Iriatherina werneri, are uniquely shaped. Their fins are sharp and angular. The swimmers have slender bodies that are markedly smaller than other varieties of rainbowfish. The reddish-orange fish prefer warm water and only grow up to two inches.

Celebes Rainbowfish

Marosatherina ladigesi, also called the celebes rainbowfish, thrive in groups. These friendly little swimmers have small, translucent bodies. Their reflective fins are blue and yellow. A blue horizontal line runs along the length of the celebes’ abdomens.

Neon Rainbowfish

Neon rainbowfish, or Melanotaenia praecox, are short, stubby bursts of color for an aquarium. The swimmers enjoy community and are happiest in schools of at least ten. The fish get their name from their bright colors; neon rainbowfish are bright blue and green with red fins.

Lake Kutubu Rainbowfish

Melanotaenia iacustris are named after their native homes. These fish hearken from Lake Kutubu in Papua New Guinea. Rich tones demarcate the swimmers, mainly blue, yellow, and teal—the male Lake Kutubu rainbowfish sports more dramatic coloration than the females.

Red Irian Rainbowfish

Red irian rainbowfish, orGlossolepis incisus, are unusually shaped. The fish have little heads and broad, flat bodies. The males are red and orange, while the female red irian rainbowfish are silver with yellow and green accents.

Lake Wanam Rainbowfish

The glossolepis anamnesis, or Lake Wanam rainbowfish, is an endangered species, only accessible from breeders. These rare swimmers aren’t as strikingly colored as their relations, but their rust-colored bodies still cut a dramatic figure.

Forktail Rainbowfish

Forktail rainbowfish, or pseudomugil furcatus, are small but visually stunning creatures. Sharp, angular fins accent their slender, silver bodies. Bright yellow fins pop brilliantly against their scales. The fish have huge, bulging blue eyes. Forktail rainbowfish like to travel in schools and hide in vegetation.

Crimson-spotted Rainbowfish

Melanotaenia duboulay garnered their common name-crimson-spotted rainbowfish from the long string of red spots gracing their abdomens. The crimson-spotted rainbowfish has a small, silvery body and is native to Australia. The swimmers help combat mosquitos in swamps and rivers.

Murray Rainbowfish

The murray rainbowfish, orMelanotaenia fluviatilis, also answers to the Australian rainbowfish. The little creatures are more subtly colored than many of their kin, but their silvery, pastel hues still contribute beautifully to an aquarium’s palette. Murray rainbowfish are: blue, yellow, green, or silver.

Redfin dwarf rainbowfish

The melanotaenia maccullochi, also called the redfin dwarf rainbowfish, does well in any aquarium. These adaptable little creatures sport gold fins with hints of green, silver, and orange accents. The redfin dwarf rainbowfish is native to Australia and has a black striped abdomen.

Parkinsoni Rainbowfish

The parkinsoni rainbowfish, ormelanotaenia parkinsoni, is a wide-bodied creature with a pointy, thin head. The swimmers are two-toned; their heads are silver, while their bodies are a vibrant, concentrated yellow.

Spotted Blue-Eyed Rainbowfish

The pseudomugil gertrudae lives up to its common name: spotted blue-eyed rainbowfish. These petite swimmers cut a striking figure. The fish is truly a hodge-podge of shapes and patterns. The spotted blue-eyed rainbowfish is silvery with vibrant yellow accents and black spots. Bulging blue eyes protrude on either side of the creature’s head.

Lake Tebera Rainbowfish

The Lake Tebera rainbowfish’s scientific name ismelanotaenia herbertaxelrodi. The yellow fish come in different gradations of the hue. The swimmers get their name from their home waters in Papua New Guinea. The Lake Tebera rainbowfish has a black stripe along its abdomen.

Sentania Rainbowfish

The sentania rainbowfish, or chilatherina sentaniensis, doesn’t entirely live up to the “rainbow” part of rainbowfish, but its red-gold color still brightens an aquarium. However, the species is critically endangered. Interested parties should ensure the fish are captive-bred.

Eastern Rainbowfish

Eastern rainbowfish, ormelanotaenia splendida spendida, are among the larger rainbowfish species. These orange and grey swimmers like to move in small schools. The eastern rainbowfish does well in brightly lit aquariums.

Distinguishing Features

Rainbowfish are readily identifiable by their brilliant, bright colors. While no two varieties have precisely the same hues, most rainbowfish have silvery iridescent fins. These swimmers only come into their full splendor as adults. Juvenile rainbowfish are duller and less vibrant than their mature counterparts.

Most varieties of rainbowfish develop a stripe while they’re attracting mates. This marking is called a courtship stipe and primarily appears on the males, though some females develop them as well. Rainbowfish all have elongated premaxillary teeth.

Left Side of Rainbowfish


Rainbowfish entered the popular consciousness as “sunfish” in 1843. That designation has since come to represent a wholly different species that shouldn’t be confused for rainbow fish.


Rainbow fish are little creatures. The majority measure below 12.7 centimeters. The fish range in size from 3 centimeters to 15 centimeters. The largest rainbow fish variety, melanotaenia vanheurni, grows up to 20 centimeters. The dwarf rainbowfish is the smallest breed, reaching a maximum of 5 centimeters.


Rainbowfish generally live between five and eight years. Larger varieties live longer lives than smaller breeds. Madagascan rainbowfish can survive up to eleven years in an aquarium.

Breeds with shorter lifespans-celebes, threadfins, and forktails-usually live under five years.

Rainbowfish live longer in clean, well-maintained aquariums.


You can identify a rainbowfish’s gender through their coloration. The males of the species are more vibrantly hued to attract females for mating.


Rainbowfish are gregarious swimmers who crave community. The creatures are peaceable and primarily non-aggressive. Rainbowfish need companionship and should be kept in schools of at least six. However, the swimmers get along well with other species and can be integrated with various non-aggressive breeds.

Ensure that rainbowfish have adequate tank space. Males can become aggressive during mating seasons, and other fish may require room to retreat.

Rainbowfish over Gravel with Plants

Tank Parameters

Tank size and requirements depend on both the breed and the number of rainbowfish. The breed needs ample room to swim in schools. Rainbowfish swim quickly and thrive when they have ample space to do so. The swimmers need an even mix of vegetation and free swimming space.

Minimum Tank Size

The absolute smallest tank rainbowfish can happily live in is 15 gallons. A 15-gallon aquarium can comfortably accommodate six small rainbowfish.

However, any rainbowfish variety exceeding three inches needs at least a 30-gallon tank. Melanotaeniids require 50-gallon or larger tanks.

Use this simple formula to select your aquarium: add two gallons to your tank for every small rainbowfish exceeding six and five gallons for each extra large rainbowfish.

Rainbowfish generally stay in the mid to upper levels of an aquarium.

Water Parameters

Rainbowfish need the water in their tanks to mimic their native habitats. The aquarium should be kept warm and provide the pets with some resistance to swim against.


Rainbowfish flourish in warm water. While the precise temperatures vary within a few degrees, the swimmers generally prefer water between 74 and 78 degrees Fahrenheit. Madagascar rainbowfish like their water a bit warmer, between 74 and 80 degrees Fahrenheit, while pseudomugilids want 76 to 82 degree Fahrenheit water.


Rainbowfish thrive in water kept at pH levels of 7.0 to 8.0 and alkalinity of 5 to 20 degrees of carbonate hardness. Madagascar rainbowfish need their pH levels to be kept between 6.5 and 7.5 with 3 to 14 degrees of carbonate hardness for alkalinity. Finally, pseudomugilids like their water with pH levels of 6.5 to 7.5 and alkalinity between 5 and 10 degrees of carbonate hardness.


Rainbowfish want low brackishness water. They can tolerate some salt but should be kept in low-salinity water. Keep the salt levels at around 1.003.

Tank Setup

For rainbowfish to thrive, they need a tank that mimics their natural environment—the pets like strong currents for fast swimming and lots of plants to hide in. Be sure to set up a tank that’s warm enough and provides plenty of protection for your fishes.


Selecting the correct substrate affects the quality of life for a fish. This substance impacts the water’s pH, alkalinity, and salinity. These features directly affect a rainbowfish’s quality of life, so choose carefully.

Darkly hued substrates allow rainbowfishes’ colors to pop. Tabling aesthetic concerns, select a substrate infused with bogwood or roots to replicate the brackish waters rainbowfish are accustomed to.


Be careful to strike a precise balance between decoration and open space. Rainbowfish like to swim in open areas. However, they also need hiding spaces. Providing ample decorations makes your rainbowfish feel more relaxed, as it gives them concealed locations. Bogwood and rocks simulate their natural habitats. Just be sure they don’t completely block the tank and remove any free swimming room.


Sufficient tank plants are essential to your rainbowfish’s happiness and well-being. Besides simulating the natural environments rainbowfish thrive in, plants provide coverage for the swimmers when they’re feeling shy or frightened. Additionally, plants offer the fish a place to mate when the season is upon them.

Choose a variety of leaf shapes and sizes. Real and artificial plants are both effective. Just be sure they don’t entirely block out free swimming space. Consider populating your tank with java moss, java fern, or wisteria.


Keep your aquarium’s light mild and provide plenty of shade. Rainbowfish flourish with a few hours of moderate morning light. Aesthetically, color-enhancing lights like red, green, or blue LEDs make a rainbowfish’s scales pop.


Rainbow fish enjoy swimming against strong currents. The experience replicates their natural environment. Choose a filter that creates powerful currents via an exemplary canister.

Powerheads ensure regular water movement in heavily decorated tanks. Be sure to check the filter regularly for blockages that could impair current activity.


Rainbowfish want warm water. They are creatures who flourish in toastier environments and need that heat to be happy and healthy. Consider the room you’re keeping your fish in. If the ambient temperature falls below 74 degrees Fahrenheit, use a tank heater to ensure the water stays at an acceptable temperature.


Rainbowfish are omnivorous. Stick to floating foods; rainbowfish are unlikely to eat food once it sinks to the bottom of the tank.

Rainbowfish in the wild eat mosquito larvae, small crustaceans, insects, and zooplankton. While you can’t replicate this exact diet in captivity, be sure to provide your rainbowfish with ample protein-rich options.

Providing live food two to three times a week will enhance your pets’ colors. Try bloodworms, daphnia, glass worms, or mosquito larvae.

Rainbowfish need to be fed small meals three times daily. Only give the swimmers as much food as they can consume within three minutes. Remove any leftovers to avoid contaminating the water.

Alternate the foods you feed your fish every few days to maximize your fish’s nutrition.

Rainbowfish from Left Side


Rainbowfish aren’t great parents, but they do breed readily and easily. Suppose breeding is your primary objective. Set up a separate tank explicitly for the purpose. The aquarium should be between five and ten gallons.

Rainbowfish don’t discriminate in who they mate with. If you have them in a tank with other fish species, they may breed with them, resulting in stunted, duller babies.

Raising the water’s temperature encourages breeding. Provide the fish with live food and keep the tank very clean. Java moss and spawning mops help set the mood for mating.

Rainbowfish matte either early in the morning or the evening. A female lays anywhere between five and 30 eggs at a time.

Rainbowfish scatter their eggs. Once they’re laid, the parents provide no protection or nourishment. Additionally, the swimmers may eat the eggs, so it’s best not to let them share a tank.

Once laid, the eggs require between one and three weeks to hatch. Keep the spawning tank’s water temperature between 78 and 80 degrees Fahrenheit to expedite the process.

Your pets display certain physical indicators when they’re ready to breed. The females get plump, and the males swim quickly around the females. Additionally, the males’ colors deepen, and they develop a dark line.

Common Diseases

A healthy fish is a happy fish, so you want to ensure your rainbowfish is at peak wellness. Certain diseases target swimmers kept close to each other. Rainbowfish are particularly susceptible to fin rot, ich, and velvet.

Fin Rot

Fin rot is precisely what the name suggests-the degeneration of the fins through infection. Fishes catch this disease via contaminated water or contact with an already-afflicted fish. Signs that your pet has fin rot include discolored fins, frayed fins, and inflammation.

Left untreated, infected fins rot and break off. Keep your tank clean and treat fin rot with antibiotics.


Fish catch ich through a parasite called icthyophthirius multifiliis. Ich is particularly damaging to fish, causing spots to develop on their fins, gills, and skin. Symptoms of ich include loss of appetite, difficulty breathing, a change in hiding behavior, and flashing.

Fish with ich need to be isolated. Keep the water clean and gradually increase the temperature to treat the infection.


Despite what the name suggests, velvet is a particularly noxious and devastating fish ailment. A parasite called oodinium causes the disease.

Velvet’s symptoms manifest as: a reddish-orange skin covering, increased gilling, flashing, and lethargic behavior. Untreated velvet causes a fish’s skin to peel off.

Velvet is highly contagious, so be sure to quarantine your fish as soon as it exhibits symptoms. Increase the water’s temperature and add copper sulfate. Velvet requires ten days of treatment.

Potential Tank Mates

Rainbowfish get along relatively well with equally relaxed fish. Choose calm, non-aggressive tankmates. Rainbowfish cohabitate best with similarly sized fish. Avoid aggressive roommates.

Male rainbowfish will compete for female attention. Fill your tank with a larger ratio of female than male fish.

Some of the best tank mate options include:

  • Angelfish
  • Danios
  • Catfish
  • Barbs
  • Mollies
  • Large tetras
  • Plecos
  • Swordtails
  • Tetras

Avoid betas and cichlids.