The dwarf rainbowfish (''Melanotaenia praecox'') is a species of

rainbowfish The rainbowfish or Melanotaeniidae is a family of small, colourful freshwater fish found in northern and eastern Australia, New Guinea (including islands in Cenderawasih Bay and Raja Ampat Islands in Indonesia), Sulawesi and Madagascar. The ...

in the subfamily

Melanotaeniinae Melanotaeniinae the Australian rainbowfishes is a subfamily of the rainbowfishes of the family Melanotaeniidae. They are a group of small, colourful, freshwater fish found in northern and eastern Australia, New Guinea, islands in Cenderawasih ...

. It is known under a number of common names including diamond rainbowfish, neon rainbowfish, Praecox rainbowfish, dwarf neon rainbowfish, peacock rainbowfish, and Teczanka neonowa. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the

Mamberamo River The Mamberamo (''Indonesian: Sungai Mamberamo'') is the second longest river on the island of New Guinea, after Sepik River (1,146 km) and third largest in Oceania by discharge (5,500 m3/s) volume after Fly River (7,500 m3/s) and Sepik (7,000 m3/ ...

basin in West Papua in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

and common in the aquarium trade.

Description

The species reaches up to in length, but there are reports of individuals up to . Males tend to be brighter in color and have deeper bodies than the females. Their bodies are bright blue and iridescent, and their fins are colorful. This species is active and is known to jump out of water.

Distribution and habitat

The species occupies small, slow-moving tributaries in regions with rainforest.

Behaviour

''M. praecox'' is considered to be

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

. This species is considered to be an egg-scatterer, so it is easy to breed. It is a schooling fish, inhabiting the areas near the surface of their native rivers. Males will fight during spawning (which happens in the early morning ), often encircling and nipping one another, along with a display by extending their fins and increasing their intensity of iridescence. Females will then spawn continuously for several days whilst the male fertilises the eggs. They will hatch within a week

In the aquarium

Despite their size, this fish requires a tank of 15 gallons or more, with a length of at least 50-60 centimetres to accommodate their energetic nature. Schools of no less than 6 should be kept, with as much as or more females than males to limit infighting and disperse aggression. Whilst they are generally peaceful, males will spar with each other or other male rainbowfish especially in the morning. This should not be an issue unless there are less females in the tank or the school is too small. They can be kept with practically any tropical freshwater fish that is not large or aggressive enough to eat them. Owing to their omnivorous habits, it is advised to feed them a varied diet, including diced leafy greens and the occasional live food such as mosquite larvae and

brine shrimp ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia L ...

as it will stimulate their instincts and enhance their colours. This species will appreciate a heavily planted tank, including floating plants to make them feel safe from what would be overhead threats in the wild. They enjoy temperatures around 25°C and a pH of 7.

References

{{Taxonbar, from=Q548082 Melanotaenia Freshwater fish of Western New Guinea Fish described in 1922 Taxonomy articles created by Polbot