Mahi Mahi (Dolphinfish)
Pelagic / BluewaterMahi mahi — dolphinfish or dorado — the spectacular blue-and-gold bluewater pelagic of WA's offshore waters. A fast-growing, surface-oriented predator that schools around floating debris, FADs, current lines and weed mats from the Gascoyne north and offshore from the lower west in summer. Blistering runs, acrobatic jumps, vivid colour, and outstanding eating.
Overview
Mahi mahi are the showpiece of WA's bluewater fishing — electric blue and gold, fast as anything in the ocean, and acrobatic enough to spend half the fight in the air. They're a warm-water pelagic that lives around structure on the open ocean: floating debris, weed mats, current lines, buoys, and the FADs (fish aggregating devices) deployed off parts of the WA coast. They follow the warm water down the coast in summer, reachable offshore from the lower west in the warm months and present year-round in the tropical north. They grow extraordinarily fast, school in good numbers (where there's one there are usually more), and are among the best eating pelagics going. Sight-casting to a lit-up bull mahi around a floating object is one of the highlights of an offshore season.
Identification
Dolphinfish, dorado, dollies, mahi
Mahi mahi are a fish, not a mammal — the old name 'dolphinfish' causes genuine alarm at the ramp, but Coryphaena hippurus has nothing to do with the bottlenose dolphin. In the water they're unmistakable: electric blue-green above, gold flanks scattered with dark spots, a long dorsal fin running from just behind the eye almost to the tail, and a deeply forked tail. Adult bulls (males) carry a tall, blunt, square forehead; cows and small fish keep a rounded head. The colour drains to dull grey-yellow within minutes of landing, so don't rely on it at the cleaning table. Small fish can be mistaken for queenfish — the full-length dorsal separates them.
How to Catch
Whole pilchards, gar, slimy mackerel, squid, live yakkas or scad pitched to sighted fish
Skirted trolling lures, small to medium pushers, deep and shallow-diving minnows, chrome slugs, soft plastics and stickbaits cast to schooled fish
30–50lb mono leader to a single 6/0–8/0 hook or gang for whole baits; no wire needed (mahi don't have cutting teeth). For casting, a 40lb leader straight to a metal or plastic. Keep a pitch rod rigged with a live bait or plastic ready — when one fish is hooked, the school often follows it to the boat.
Troll skirts and minnows along current lines, temperature breaks and past any floating structure — debris, weed mats, buoys, FADs — at 6–8 knots. When you raise a fish, keep it hooked and in the water boatside; the rest of the school will hang under it, and you can pick them off with pitched baits and plastics. Sight-cast to fish holding around floating objects. They run hard and jump repeatedly, so keep the line tight through the aerials.
November through May in the lower west as the warm water pushes south, and year-round in the tropical north. The warm-water months and the period after summer storms (which scatter floating debris and weed) are prime. Early morning over current lines and around FADs is the best window.
Up to 2m and 30kg+, commonly 3–10kg
Nov–May (warm-water months); year-round in the tropical north
Size & Growth
Most WA mahi are 3–10kg and somewhere between 70cm and a metre. A good fish off the lower west in summer is 8–12kg; a bull over 15kg is a very good one, and the headline 2m, 30kg-plus fish are rare anywhere and rarer here. They grow astonishingly fast — a mahi can go from egg to several kilos inside its first year — and they live fast too, with a lifespan measured in a handful of years rather than decades. That's why a school tends to be a single size class: if the fish around a weed mat are rats, they'll all be rats.
Diet & Habitat
Mahi are surface-oriented predators that eat flying fish, small pelagic baitfish, juveniles sheltering under floating cover, squid and pelagic crabs. They live around structure on the open ocean rather than reef: weed mats, floating debris, ropes, buoys, FADs and the rubbish lines that gather on current and temperature breaks. In WA they're present year-round in the tropical north — off Exmouth, Onslow and the Pilbara islands — and push down the lower west coast with the warm water, reachable offshore from Perth and the South West roughly November to May. After summer storms scatter weed and debris offshore, the fishing improves markedly.
WA Size & Bag Limits
| Minimum size | 50 cm |
|---|---|
| Bag limit | 3 — within the large pelagic finfish mixed bag |
| Counts toward | Counts within the statewide large pelagic finfish mixed daily bag of 3. Specific rules apply around FADs — check current arrangements. |
Mahi mahi (Coryphaena spp.): minimum size 500mm, within the statewide large pelagic finfish mixed daily bag of 3. Note that FADs are fitted with specific rules — check current arrangements.
Eating Quality
Outstanding — one of the most prized eating pelagics in WA waters. Firm, moist, white-to-pink flesh with a clean, mild flavour and large flakes that hold together on the grill, in tacos, in a curry or raw as ceviche. Bleed and ice on capture; the brilliant colours fade within minutes of landing, but the eating quality holds. Size makes little difference to quality — a 3kg rat eats as well as a 12kg bull, the bigger fish just gives you thicker loins to work with. Skin it, trim the dark bloodline strip and don't overcook it; mahi is lean and turns dry and cottony the moment it's past done. Vacuum-sealed loins freeze better than most pelagics, though it's clearly a fish to eat fresh. Mercury isn't a concern in a fish that lives this fast and this short.
Perth Tips
Offshore from Perth and the South West in summer, the FADs and any floating structure are the first places to look; in the north, mahi show year-round on the current lines off Exmouth, Onslow and the Pilbara islands. Keep one hooked fish in the water to hold the school. Bull (male) mahi grow the big square forehead and the biggest fish; both sexes eat equally well. Don't waste the colour show — but get them bled and iced fast.