Mahi-Mahi & Dog-Tooth Tuna: WA's Summer Bluewater

Mahi-mahi (Coryphaena hippurus) are unmistakable — vivid blue and electric gold, blunt-headed, and built like a flattened torpedo. Bull (male) fish develop a tall, square forehead and grow the biggest; both sexes eat equally well. They’re a fast-growing, short-lived, surface-oriented predator that lives its whole life around structure on the open ocean: weed mats, current lines, floating debris, buoys, and the FADs. Where there’s one, there are usually several — they school under floating objects, and a single hooked fish kept in the water will hold the rest of the school boatside.

They run hard, jump repeatedly, and fade from neon to dull grey within minutes of being landed. The colour show is the price of admission; the eating is the reward.

Dog-tooth tuna (Gymnosarda unicolor) are a different animal entirely. Despite the name, they’re not an open-water roamer — they’re a reef tuna, holding tight to steep drop-offs, current-swept bommies and outer-reef edges through WA’s tropical north. They have a thick, muscular build and a reputation that precedes them: hook one and it sounds, dragging you straight back into the coral it came from. Plenty of anglers hook their first dog-tooth and never see it.

They’re a northern fish — Ningaloo, the Mackerel and Montebello Islands, the Pilbara and Kimberley drop-offs. You won’t find them off Perth. Eating quality is only fair, so most captures are photographed and released, or kept for the sheer rarity of landing one.

For mahi at the FADs, troll skirted lures and diving minnows along current lines and past any floating structure at 6–8 knots — small to medium pushers, chrome slugs, and shallow- and deep-diving minnows all work. The moment you raise a fish, the tactic changes: keep that fish hooked and in the water boatside, and the school will stack underneath it. Then pick them off with pitched baits — whole pilchards, gar, or live yakkas — and plastics or stickbaits cast into the pack. Keep a pitch rod rigged and ready; the school doesn’t wait.

Rigging is forgiving — mahi don’t have cutting teeth, so 30–50lb mono leader to a single 6/0–8/0 hook (or a gang for whole baits) is plenty, and 40lb straight to a metal for casting. No wire needed.

Dog-tooth are a heavier proposition. They’re taken jigging and live-baiting the drop-offs, and the gear has to be locked-up brutal — they give you one or two runs to turn their head before they reef you, and if you don’t, you lose. This is genuinely heavy tackle: stout overheads, 80lb-plus braid, and a drag set to stop a freight train.

Mahi-mahi is outstanding — firm, moist, white-to-pink flesh with a clean, mild flavour that takes to the grill, the pan, tacos or a fresh ceviche. It’s one of the most prized eating pelagics in WA. Bleed and ice it the moment it’s aboard. Dog-tooth, by contrast, is only fair eating; it’s a fish you chase for the fight and the rarity, not the fillet.

Mahi-mahi carry a minimum size of 500mm and sit within the statewide large pelagic finfish mixed daily bag limit of 3 — a single bag of 3 shared across mackerel, wahoo, tuna, cobia and barracuda. Dog-tooth tuna falls within that same mixed pelagic bag of 3. So a day’s bag might be two mahi and one dog-tooth, or any other mix up to three — not three of each.

FADs are fitted with their own specific rules, so check the current FAD arrangements before you fish them. And because mahi fishing is boat-based offshore work, you’ll need a Recreational Fishing from Boat Licence (RFBL) to fish from a powered boat — required even if you release everything.

Limits and FAD rules change, so confirm the current figures with DPIRD before you head out.

Mahi turn up the moment the water warms — get the trolling spread sorted, watch the mahi-mahi forecast, and run wide on the first calm summer morning.