Aquendium

Boeseman's Rainbowfish

Melanotaenia boesemani

Also known as: Boesemani rainbow, Bicolour rainbowfish

Quick Facts

  • Adult size: 9-11 cm (3.5-4.3 inches)
  • Minimum tank size: 150 litres (40 gallons)
  • Lifespan: 5–8 years
  • Temperament: peaceful
  • Swimming level: middle-and-top
  • Diet: omnivore
  • Minimum group size: 6
  • Difficulty: intermediate

Water Parameters

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

Care Summary

A West Papuan rainbowfish from the Ayamaru Lakes, and one of the few aquarium fish whose body is split into two colours: blue-grey at the head, orange-red at the tail. The colour is slow to arrive. Juveniles in shop tanks are a drab silver, which leads many keepers to pass them over; mature males in a settled group are a different animal entirely. They are active, durable, and long-lived, with a strong preference for the hard, alkaline water that suits much of Australia. The main requirements are swimming length, a group to draw out the colour, and patience for that colour to develop over several months. A heavily-planted tank with open swimming lanes shows them best.

Tankmates

A peaceful, hard-water schooling fish that suits much of Australia's naturally hard tap water without adjustment. Keep in groups of at least six: males develop their best colour competing with one another, and a lone or paired rainbow is a washed-out, nervous version of the fish. Their adult size and constant activity call for a long tank and similarly-sized, non-aggressive companions; very small nano fish and shrimp are out of place and may be eaten or simply outpaced at feeding. Excellent alongside other rainbowfish, larger tetras, peaceful barbs, and sturdy catfish.

Compatible with

Avoid keeping with

Common Problems

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

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