Blue-threadfin
Blue threadfin — called blue salmon by most anglers up north — are a tropical estuary fish found across northern Australia from Exmouth Gulf in WA around to southern Queensland.
They're a serious light-tackle target in the NT and Gulf of Carpentaria, where they patrol shallow tidal flats and mangrove edges. Fast-growing and short-lived, they're also excellent table fish with thick, boneless fillets.
Scientific Name: Eleutheronema tetradactylum
Also known as Blue Salmon, Bluenose Salmon, Cooktown Salmon, Burnett Salmon, Colonial Salmon, Rockhampton Salmon, Fourfinger Threadfin, Tassel-fish
- Thick-bodied with a blunt, small head that looks almost out of proportion to the body — unmistakable once you've seen one. Silvery-blue above, pale below.
- The giveaway feature: four long, free-hanging filaments (threadfins) below the pectoral fin — these are sensory organs used to detect prey in murky water.
- Smaller than the related king threadfin; blue threadfin top out around 80 cm and are commonly caught between 40–65 cm.
What to know
Habitat Distribution
- Native to Australia; range runs from Exmouth Gulf in WA clockwise around the entire northern coastline to around Sandy Cape in southern Queensland.
- Adults favour shallow coastal waters over muddy or sandy bottoms, rarely venturing deeper than 10 m — making them accessible from shore and small boats alike.
- Juveniles use estuaries heavily; adults are found throughout tidal river mouths, mudflats, and mangrove-lined creeks across the NT, Gulf of Carpentaria, and coastal Queensland.
- Stocks in QLD (East Coast and Gulf of Carpentaria) and the NT are classified as sustainable; WA catch is negligible.
Key Locations
- Gulf of Carpentaria (QLD/NT) — one of the most productive blue salmon fisheries in Australia, with large shallow tidal systems and extensive mangrove habitat.
- Northern Territory coastal estuaries — rivers and tidal creeks around Darwin and the Top End hold good populations accessible from shore and small boats.
- East Coast Queensland — from the Gulf coast down to around the Burnett River region; the Burnett and Mary River systems are historically associated with the species.
- Exmouth Gulf, WA — the southern edge of the range; fish are present but catches are negligible compared to NT and QLD.
Specific Spots
- Tidal drop-offs and gutters adjacent to mudflats — as the tide falls, bait gets pushed off the flats and blue salmon stack up waiting at the edge.
- Mangrove points and creek mouths where current funnels bait into a predictable lane; fish hold just inside the current break.
- Shallow sandy or muddy holes in the lower reaches of tidal rivers — blue salmon use these as staging areas between feeding runs on the flats.
- Spring tides (around full and new moon) concentrate fish and bait most effectively; the bigger the tidal movement, the more active the bite.
Blue-threadfin FAQ
Answers from onWater's species guide.
What are the best lures and bait for Blue-threadfin?
Soft-plastic paddle tails and curl-tail grubs on 1/4–1/2 oz jig heads are the go-to lure for working tidal gutters and drop-offs, bounce them along the bottom and let the current do the work.
What flies work for Blue-threadfin?
Clouser Minnows (which imitate small baitfish) in white, chartreuse, or natural colours are the most reliable pattern, the weighted eyes get the fly down quickly in tidal current.
When is the best time to fish for Blue-threadfin?
Dry season (roughly April–October) is the prime period across the NT and northern QLD, stable, clear conditions and concentrated bait make fish more predictable.
How do you catch Blue-threadfin?
Most anglers target blue salmon from the shore or a small dinghy, working tidal gutters and mangrove edges on the falling tide with soft plastics or live prawns. Wading the shallow flats at low light and casting to the edges of drop-offs is a productive approach in the NT and Gulf country.
What do Blue-threadfin eat?
Primarily small fish and prawns, the long sensory filaments help them locate prey by feel in turbid, low-visibility water. Match this with soft-plastic paddle tails or curl-tail grubs in natural baitfish colours, or live/fresh prawns fished on the bottom near structure.
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