15 Different Tropical Aquarium Rainbowfish - Rare & Common

Rainbowfish are colourful, small freshwater fish and are made up of two main groups.

The first group contains the Families Bedotiidae and Melanotaeniidae, which include larger, active fish in the genera Melanotaenia, Glossolepis and Bedotia. An anomaly is the tiny Threadfin Rainbow, I. werneri, which should be treated like a Pseudomugilid.

The second group covers the Families Telmatherinidae and Pseudomugilidae. Pseudomugilidae is made up of smaller, more docile fish, often referred to as "Blue Eyes". The Family Telmatherinidae consists of a single species, the Celebes Rainbowfish. You will understand how Rainbowfish get their name once you see a school of brilliantly coloured adult Melanotaeniids.

Most rainbowfish species are less than 12 cm in length, with some species measuring less than 6 cm, while one species, Melanotaenia vanheurni, reaches up to 20 cm.

Their teeth distinguish the Melanotaeniidae; their distal premaxillary teeth are enlarged. They have a tight body with the two dorsal fins being separated but only a little gap. The lateral line is usually weakly developed or absent.

They have relatively large scales, and their pelvic fins are attached to the abdomen by a membrane that runs along the length of the innermost ray. You can use this feature to separate Rainbowfishes from Silversides; however, the membrane is regularly torn.

The majority of the family species demonstrate sexual dysmorphism, males usually being the more colourful sex, slightly larger than females and exhibiting an elongated median fin ray. The same is true with age; the older they get, the more vibrantly coloured they become.

Natural habitat

Rainbowfish are indigenous to northern and eastern Australia, Papua New Guinea and also on the islands in Cenderawasih Bay and Raja Ampat in Indonesia as well as Madagascar. They inhabit streams, lakes, rivers and swamps. Some Rainbowfish populations have become endangered by the introduction of invasive species and human activity. Most Rainbowfish available in the hobby today are produced commercially on farms in Florida and Southeast Asia.

Behaviour

Rainbowfish are peaceful yet active and do well with most similarly sized, non-aggressive fish. You can mix different species. You can also keep them with gentle Barbs, larger Tetras, Danios, Rasboras, Catfish and even non-aggressive Cichlids such as Kribensis, making them excellent aquarium community members.

Rainbowfish are shoaling fish; therefore, you should keep them in groups of 6 or more individuals for the most desirable effect. Males will exhibit their best colours as they compete for attention from females. However, two males may sometimes fight during the breeding season if there are not enough females.

Pseudomugilids and Threadfin Rainbows are sometimes shy and docile, so make sure you choose their tankmates carefully. These can include small Tetras, Pygmy Rasboras, Peaceful barbs, Otocinclus and Corydoras Catfish.

In the aquarium

Rainbowfish are active and need plenty of swimming space. Smaller species like the Neon Dwarf Rainbow and the Celebes Rainbow will thrive in a 110-litre aquarium. In contrast, many other Rainbowfish need an aquarium of at least 190 litres or larger. Sufficient cover such as tall plants and other structures is essential, but you should provide open swimming areas as well. The "Blue Eyes" and Threadfin Rainbows are perfectly happy in community aquariums of 75 litres or well-planted species tanks of 40 litres or less.

A majority of Rainbowfish come from hard, alkaline water, but captive-bred fish available today will thrive in a wide range of water conditions. They do best between 74 degrees Fahrenheit and 78 degrees Fahrenheit with a pH between 7.0 and 8.0 and alkalinity between 90 ppm and 360 ppm. Madagascar Rainbowfish come from more acidic water and should be kept between 74 degrees Fahrenheit and 80 degrees Fahrenheit with a pH of between 6.5 to 7.5 and alkalinity between 55 to 250 ppm. Pseudomugilids prefer temperatures between 76derees Fahrenheit and 82 degrees Fahrenheit with a pH between 6.5 to 7.5 and alkalinity between 90 ppm to 180 ppm.

If you keep your aquarium in a room with a temperature below 74 degrees Fahrenheit, it is advisable to use an aquarium heater to maintain the correct temperature. Ensure you have a sound filtration system and provide water changes weekly. Don't forget to use a de-chlorinator if you are using tap water.

Breeding

It is pretty straightforward to breed Rainbowfish. They are egg scatterers and present no parental care once the eggs are laid. Most Rainbowfish spawn in vegetation, but you can provide spawning mops as an alternative.

Although Rainbowfish spawn all year round, they lay a considerable number of eggs at the start of the local rainy season. A slight increase in temperature and conditioning them with live and frozen foods will often encourage spawning activity.

Rainbowfish Eggs will hatch within 7 to 18 days, depending on the species and the temperature.

Once the Rainbowfish larvae hatch, they will absorb their yolk sacs. Once the egg sacs have been entirely consumed, they will then be able to swim freely and move towards the water's surface. Once the fry reaches the surface of the water, you can then feed them infusoria type foods, spirulina water, plankton, and liquid foods.

Feeding

In their natural habitat, Rainbowfish are omnivores feeding on insect larvae, small crustaceans and algae. In captivity, Rainbowfish require both meat-based foods and vegetable matter in their diet.

Melanotaeniids will thrive on high quality dried foods such as spirulina flakes, tropical Flakes, granules and algae wafers. In contrast, Pseudomugilids will accept these foods and may need a higher proportion of frozen and live foods to promote optimum colour and health.

You should rotate their diet daily for maximum results and feed them only what they can consume in 2 minutes or less twice a day.

Frquently asked questions about the Rainbowfish

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