Dwarf neon rainbow fish:

The dwarf neon rainbow fish are endemic to the Mamberamo river system, New Guinea, Indonesia. This is one of the largest river systems on the island, being over 2000 km long.They Tends to inhabit swiftly flowing tributaries off the main river, as well as surrounding swamps and marshes. 

The fish congregate around areas of aquatic vegetation, or submerged roots and logs.
An active species, so despite its small size it requires an aquarium measuring at least  55 litres.(60cm x 30cm x30cm) 
This little rainbowfish is ideally suited to a heavily planted setup and will show its best colours in such surroundings. It doesn’t appreciate bright conditions and we suggest the use of floating plants to diffuse the light entering the tank. Allow open spaces between areas of planting to allow swimming space and areas for males to display at one another. High water quality is essential to the well-being of this species, so weekly partial water changes are recommended.
Like most of its congeners, it’s an unfussy, omnivorous species and will accept most dried, frozen and live foods. Regular feedings of the latter will help to ensure the fish exhibit their best colours.

Mature males are larger and exhibit brighter colouration than females. They also develop a much deeper body than females as they grow.
The adult fish are best conditioned as a group in a separate aquarium with plenty of live and frozen foods. As the fish come into condition, the females will appear noticeably plumper, and males will display to each other almost constantly. Select the fattest, best-coloured pair for breeding and introduce them to thespawning tank. A small raise in temperature can often induce spawning. The pair will spawn for a period of several weeks, laying batches of eggs each day. These are attached to surfaces by a small thread. The adults tend to eat the spawn, and it’s easier to raise the fry in a separate aquarium, so we recommend checking the plants or mops regularly and removing any eggs you find to a raising tank containing water from the spawning tank. The eggs hatch in 7-10 days, depending on temperature. The minute fry initially require infusoria-type food, before graduating onto free swimming foods, such as brine shrimp nauplii, after a week or so. Sinking foods are unsuitable as the fry tend to stay very close to the water surface.Brood size is usually a little larger than with other rainbowfish.

REFERENCES:

Rainbowfishes: Their Care and Keeping in Captivity by Adrian R. Tappin

http://www.seriouslyfish.com/species/melanotaenia-praecox/