Murray River Rainbowfish
Melanotaenia fluviatilis
Also known as: Australian rainbowfish, Murray rainbowfish, Crimson-spotted rainbowfish
Quick Facts
- Adult size: 8-11 cm (3.1-4.3 inches)
- Minimum tank size: 110 litres (29 gallons)
- Lifespan: 5–8 years
- Temperament: peaceful
- Swimming level: middle-and-top
- Diet: omnivore
- Minimum group size: 6
- Difficulty: beginner
Water Parameters
- Temperature: 16–26°C
- pH: 7–8.5
- Hardness (GH): 143–357 ppm (8–20 dGH)
Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.
Care Summary
One of Australia's own rainbowfish, native to the temperate Murray-Darling river system, and a hardy, handsome, and quietly patriotic choice for a local community tank. Less gaudy than the imported Boeseman's rainbow but no less appealing once mature, the males develop warm orange-red fins and a silvery, crimson-flecked body that brightens during display. Its great practical virtues for Australian keepers are its tolerance of cool water, which suits unheated tanks in southern states, and its preference for hard, alkaline conditions, which match the tap water straight from the supply in much of the country. Active, peaceful, long-lived, and undemanding, it is an excellent native centrepiece and a natural anchor for a Murray-Darling or general hard-water biotope alongside pacific blue eyes and other local species. A genuine showcase of Australian freshwater fauna.
Tankmates
A hardy native schooling fish, peaceful and adaptable, and a natural centrepiece for an Australian native or hard-water community. Keep it in a group of at least six, where the males flush with colour and display. Its tolerance for cool water (it hails from the temperate Murray-Darling system) and hard, alkaline conditions makes it ideal for unheated or lightly-heated tanks and for the hard tap water of much of the country, pairing naturally with other natives like pacific blue eyes, with cool-water community fish like white clouds and rosy barbs, and with other rainbowfish. Like most rainbows it has a modest mouth but will eat the smallest nano fish and shrimp, so keep tankmates of reasonable size. Avoid fin-nippers and warm-water-only species such as discus.
Compatible with
- Rosy Barb
- Gold Barb
- Pristella Tetra
- Pacific Blue Eye
- Bristlenose Pleco
- Bronze Corydoras
- Boeseman's Rainbowfish
- Dwarf Neon Rainbowfish
Avoid keeping with
- Betta
- Ember Tetra
- Chili Rasbora
- Cherry Shrimp
- Fin Nippers
Common Problems
- dull colour in small groups
- predation on the smallest nano fish and shrimp
- fin nipping from inappropriate tankmates
- ich
Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20