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EveryFish
Murray River Rainbow Fish (Melanotaenia fluviatilis) at Adelaide Zoo 13 November 2011

Murray River rainbowfish

Colourful freshwater fish from southeastern Australia.

Photo: Bahudhara, CC BY-SA 3.0, via Wikimedia Commons

The Murray River rainbowfish is a small, vibrant freshwater species native to southeastern Australia. It is the southernmost rainbowfish, adapted to cooler winter temperatures in the Murray-Darling basin. Popular in aquariums for its bright colours and peaceful schooling behaviour, it was formally distinguished from similar species in 1986.

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  • Southernmost rainbowfish species
  • Survives winter temps of 10-15 °C
  • Males are larger and more colourful
  • Popular peaceful aquarium fish
  • Recognised as distinct species in 1986

What it is

This small freshwater fish features an elongated body with a small head and large eyes. Males grow larger and display more vivid colours than females. The sides shine with silver or green hues, marked by a blue stripe running from snout to tail. Fins are yellow with dark edges and orange or red spots. Males develop extra orange stripes on their rear half during breeding. Two dorsal fins and a shallowly forked tail complete its appearance.

Where it lives

Native to southeastern Australia, this species lives west of the Great Dividing Range. Its primary home is the Murray-Darling basin in New South Wales and southern Queensland. The Campaspe and Goulburn Rivers in Victoria mark its southern limit. It thrives in slow-moving rivers, wetlands, and billabongs. Uniquely among rainbowfish, it tolerates winter temperatures dropping to 10–15 °C in the lower Murray River.

How it lives

These omnivores eat aquatic and land-based invertebrates along with filamentous algae. In tanks, they accept live foods and flakes. They are peaceful creatures that school near logs and grassy banks. Stress may cause them to nip fins, so keeping them away from long-finned tank mates is wise. A group of at least six helps maintain their natural schooling behaviour and reduces stress.

Breeding and life cycle

Breeding this species is considered easy for hobbyists. They should be kept in groups to encourage natural behaviour. While specific spawning details in the wild are not detailed here, their adaptability makes them straightforward to breed in captivity. Sexual dimorphism is clear, with males showing brighter colours and red spots on fins when ready to breed.

Murray River rainbowfish
A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

Aquarium enthusiasts value this fish for its bright colours and active schooling nature. It is a popular choice for community tanks due to its generally peaceful temperament. Care must be taken to avoid housing them with long-finned species, as stressed individuals may nip. Their ability to survive cooler water temperatures makes them unique among rainbowfish kept in home aquaria.

Questions people ask about Murray River rainbowfish

How big do Murray River rainbowfish get?

They reach a maximum length of 11 cm. Males typically grow to 8.5 cm, while females are smaller, usually reaching only 7 cm in length.

What temperature do they need?

They prefer water between 22 and 25 °C. However, they are unique among rainbowfish for surviving winter temperatures as low as 10–15 °C in their native range.

Are they good for community tanks?

Yes, they are peaceful and school well. However, they may nip fins when stressed, so it is best to avoid keeping them with long-finned fish species.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Murray River rainbowfish", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

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Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

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