Riffle Galaxias
The Riffle Galaxias is a small, cryptic native fish restricted to cool upland streams in north-eastern Victoria. It wasn't formally described as its own species until 2014, having long been confused with Mountain Galaxias.
Anglers rarely target it directly — it's more likely to turn up as an incidental find when sampling or snorkelling clear riffle habitat. Its significance is conservation, not catch.
Scientific Name: Galaxias arcanus
Also known as Galaxias sp. 2, Galaxias sp. 3
- Olive-brown to beige body with irregular dark blotches or bands across the back; head and snout noticeably darker, often dark grey — no black bars along the lateral line.
- Distinctive bulbous upper lip overhangs a noticeably shorter lower jaw; the snout projects forward, giving the face a blunt, subterminal look unlike most other galaxiids.
- Body is shallow and flat-profiled with a long, slender caudal peduncle that's longer than the tail fin itself — a key ID feature separating it from Mountain Galaxias.
- Small fish: most run 60–75 mm, with a recorded maximum around 98 mm and a max weight of about 6 g.
What to know
Habitat Distribution
- Endemic to Australia — found only in a narrow band of upland streams on the northern slopes of the Great Dividing Range in north-eastern Victoria.
- Range runs from the upper Murray River headwaters west through the Acheron and Goulburn River systems, at elevations roughly between 150 and 880 m.
- Lives in cold to cool, clear, fast-flowing creeks and rivers — shallow riffles and high-energy runs are its core habitat, not pools or slow water.
- Juveniles have been recorded moving upstream through slow, shallow pool edges, but adults stick to fast water over cobble and pebble beds.
Key Locations
- Upper Murray River headwaters, north-eastern Victoria — the eastern end of the species' known range.
- Goulburn River system, north-eastern Victoria — part of the documented distribution band on the northern slopes of the Great Dividing Range.
- Acheron River catchment, Victoria — western extent of confirmed records.
Specific Spots
- Cobble and pebble riffles are the primary address — adults shelter among or directly under rocks, or deeper in the gaps between substrate, where current is broken and cover is tight.
- Bedrock shelves and boulder runs adjacent to riffles also hold fish, particularly where interstitial spaces give refuge from predators and flow.
- Avoid deep pools and slow runs; this species is almost entirely a riffle and fast-run fish in its adult stage.
Riffle Galaxias FAQ
Answers from onWater's species guide.
How do you catch Riffle Galaxias?
This species is not targeted by recreational anglers. It is primarily encountered by researchers, conservation biologists, and anglers who notice small galaxiids while fishing or snorkelling clear riffle habitat in north-eastern Victorian streams.
What do Riffle Galaxias eat?
As a small benthic galaxiid in fast riffle habitat it likely feeds on aquatic invertebrates, small mayfly nymphs, midge larvae, and other stream insects dislodged from cobble substrate.
Where do Riffle Galaxias live?
Endemic to Australia, found only in a narrow band of upland streams on the northern slopes of the Great Dividing Range in north-eastern Victoria. Range runs from the upper Murray River headwaters west through the Acheron and Goulburn River systems, at elevations roughly between 150 and 880 m.
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