Neon Rainbowfish

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Melanotaenia praecox - (Weber & Beaufort, 1922)
Neon Rainbowfish

An unusual dwarf rainbowfish, best kept in groups three to six or more. Plain juveniles mature into glimmeringly beautiful adults. Neil Hepworth


This is the ugly duckling of the tropical fish world: juveniles are drab and the fish only reach their beautiful coloration as they mature. This is an active schooling species that does best when kept in groups of at least three and preferably six. It is ideal if the ratio is two females to one male, but this is difficult to ensure when buying a group of young fish. Older males develop high backs.

Other common name(s):

  • Praecox Rainbowfish
  • Dwarf Neon Rainbowfish

Native range:

Habitat: Plant the tank on the sides and back and provide a cover of floating plants. A dark gravel substrate accents coloration. Allow ample open swimming space.

Maximum length: 5 cm (2 in)

Minimum aquarium size: 76 L (20 gal)

Water: Freshwater 22 °C (72 °F) - 26 °C (79 °F)

General swimming level: Midwater to top.


M. praecox thrives on live foods, such as bloodworms, glassworms, brine shimp, etc., frozen, and prepared foods. Provide a varied diet.

Aquarium Compatibility

They’re great in a peaceful community tank, but not with timid or delicate species as they can be intimidating.


Both sexes are vividly colored but the males do have redder fins while the fins of the females tend to range from yellow to red. A pair will scatter their eggs among the plants, several times a day as with the Banded Rainbowfish. The eggs are unusual as they can be collected and stored to hatch out later.


A well-fitted tank cover will prevent leaping losses.

Image credit: NH
Text credit: KW