The largest rainbowfish genus and the type of the family, Melanotaenia, derives from the ancient Greek melano (black) and taenia (banded).

Translated, it means "black-banded", and is a reference to the often striking lateral black bands that run along the bodies of those in the genus Melanotaenia.

The majority of the species in this family demonstrate conspicuous sexual dimorphism, with the males usually being the more colorful sex and also showing an elongated median fin ray.

In the wild, some rainbowfish populations have been severely affected by the aggressive introduced eastern mosquitofish (Gambusia holbrooki), tilapia cichlids, and pollution.

M. ajamaruensis, M. arfakensis, M. boesemani, M. longispina, M. manibuii, M. misoolensis, M. multiradiata, M. susii) Southern Bird's Head clade (incl.

In a home setting, these fish need well-oxygenated water with a pH level of 6.8 – 7.2, optimal temperatures varying between 72 and 82 °F (22–28 °C), and plenty of aquatic plants to give them hiding places amid their school.