Additional information (Wiki): Rainbowfish are usually less than 12 centimetres (4.7 in) in length, with some species measuring less than 6 centimetres (2.4 in), while one species, Melanotaenia vanheurni, reaches lengths of up to 20 centimetres (7.9 in). They live in a wide range of freshwater habitats, including rivers, lakes, and swamps. Although they spawn all year round, they are lay a particularly large number of eggs at the start of the local rainy season. The eggs are attached to aquatic vegetation, and hatch 7 to 18 days later. Rainbowfish are omnivorous, feeding on small crustaceans, insect larvae, and algae.

Rainbowfish are popular aquarium fish along with blue eyes (genus Pseudomugil), which are another small colourful fish found in a similar range and habitats. Rainbowfish populations in the wild have been severely affected by the aggressive introduced eastern mosquitofish (Gambusia holbrooki).