Dwarf Neon Rainbowfish

Melanotaenia praecox

Also known as: Praecox rainbowfish, Neon dwarf rainbow, Dwarf rainbowfish

Water Parameters

• Temperature: 22–28°C
• pH: 6.5–8
• Hardness (GH): 89–268 ppm (5–15 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

The rainbowfish for tanks that cannot house the larger species: a stocky, palm-sized fish that glows a remarkable electric blue, brightest in mature males kept in a group and competing for attention, set off by red-orange fins. Where most rainbowfish need a metre of tank, the dwarf neon is happy in a standard community aquarium, which has made it one of the most popular rainbows in the hobby. It is hardy, active, peaceful, and undemanding, with a particular tolerance for the hard, alkaline water common across Australia, and it brings constant movement and colour to the middle and upper levels of a planted community tank. Buy a group, give it a week or two to settle, and the drab silver fish from the shop tank becomes a living shard of blue.

Tankmates

A small, peaceful, active rainbowfish that schools best in a group of six or more, where the males intensify to an electric blue and display to one another, jostling without harm; in small groups they are washed-out and dull. Far more community-friendly than the larger boesemani rainbow, they suit a planted tank with open swimming space and a mix of peaceful, similarly-sized tankmates: tetras, rasboras, corydoras, peaceful gouramis, and other rainbowfish. Their adaptability to harder, alkaline water makes them an excellent match for much of Australia's tap supply and for hard-water tankmates. Keep them away from fin-nippers, which target their fins, and from anything large enough to eat them. Mostly safe with adult shrimp, though shrimplets may be taken.

Compatible with

• Harlequin Rasbora
• Pristella Tetra
• Bronze Corydoras
• Bristlenose Pleco
• Honey Gourami
• Otocinclus
• Boeseman's Rainbowfish

Avoid keeping with

• Betta
• Tiger Barb
• Serpae Tetra
• Large Cichlids
• Fin Nippers

Common Problems

• dull colour in small groups or undersized tanks
• slow colour development mistaken for poor stock
• fin nipping from inappropriate tankmates
• ich

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20