Two-Spined Blackfish
Two-spined blackfish are a small, secretive native fish of the cool upland streams in north-east Victoria, south-east New South Wales, and the ACT.
They're not widely targeted, but on light tackle in clear mountain water they're a genuine find — a native species tied tightly to healthy, boulder-strewn streams in the Murray-Darling headwaters.
Scientific Name: Gadopsis bispinosus
Also known as Slippery, slimy, blackfish
- Brown to olive-green body with bold dark 'giraffe' spots; creamy or light-grey belly; covered in tiny scales under a thick mucous coating — hence the 'slimy' nickname.
- Long, low dorsal fin running almost to the tail; pelvic fins reduced to a pair of thin white filaments under the throat — a distinctive feature shared with river blackfish.
- Key ID point over river blackfish: the dorsal fin has 1–3 spines (usually 2), versus 7–13 in river blackfish, though the difference can be subtle in hand.
- Most fish run 150–170 mm; anything over 250 mm is a good one, with a hard maximum around 325 mm and 195 g.
What to know
Habitat Distribution
- Native and endemic to Australia — restricted to the south-east corner of the Murray-Darling system: north-east Victoria, south-east NSW, and the ACT.
- Found in cool, clear, fast-flowing upland and sub-alpine streams with cobble, boulder, and rocky substrate; generally absent from tiny headwater trickles and very shallow, high-velocity runs.
- Also present in upland reservoirs where rocky margins provide suitable cover — but stream populations are the core of the range.
- Strongly associated with forested catchments; sediment from erosion or agriculture degrades habitat quickly, so clean water is a reliable indicator of where they'll be.
Key Locations
- Brindabella Ranges, ACT/NSW border — core habitat with documented populations in upland tributaries of the Murrumbidgee system.
- North-east Victoria upland streams — the King River catchment near Cheshunt is the type locality where the species was first formally described.
- South-east NSW upland tributaries of the Murray-Darling headwaters — cool, rocky streams in forested catchments hold the bulk of NSW populations.
Specific Spots
- Boulder and cobble patches with gaps and crevices — two-spined blackfish use the spaces between rocks as both shelter and feeding stations, especially at night.
- Submerged timber and woody debris in medium to large streams; they tuck tight against structure and rarely venture into open water.
- Current breaks behind large boulders or undercut banks where flow slows — fish hold here to avoid expending energy and intercept drifting invertebrates.
- Rocky margins of upland reservoirs, particularly where boulders meet deeper water — fish move along these edges rather than holding in open, featureless areas.
Two-Spined Blackfish FAQ
Answers from onWater's species guide.
What are the best lures and bait for Two-Spined Blackfish?
Small soft-plastics (grubs, worm-style baits) worked slowly along the bottom near boulders and timber; keep the presentation close to structure rather than retrieving through open water.
What flies work for Two-Spined Blackfish?
Nymphs are the go-to: Pheasant Tail nymphs imitate mayfly larvae, and Hare's Ear or caddis larva patterns cover caddisfly larvae, dead-drifted (allowed to drift naturally with the current, no added movement) through rocky runs and along boulder edges.
When is the best time to fish for Two-Spined Blackfish?
Autumn and winter (April–August), cooler water concentrates fish in deeper pools and around structure; feeding activity continues but is slower. Spring (September–November), fish become more active as water warms ahead of spawning; pre-spawn fish can be found in shallower rocky runs.
How do you catch Two-Spined Blackfish?
Most anglers encounter two-spined blackfish incidentally while fishing for trout or other natives in upland streams. Those targeting them deliberately fish after dark with light spin gear or nymphs worked tight to boulders and woody debris, where fish hold close to structure rather than roaming open water.
What do Two-Spined Blackfish eat?
Aquatic insect larvae are the main food, mayflies, caddisflies, and midges dominate. Small flies and nymphs imitating these (Pheasant Tail nymphs for mayflies, Hare's Ear or caddis larva patterns for caddisflies) are the logical starting point on fly gear.
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