Cobia
Pelagic / OffshoreCobia are a curious, structure-loving pelagic of WA's north — found from Kalbarri up through the Gascoyne, Pilbara and Kimberley, and often mistaken for a shark or a giant remora on first sighting. They hold tight to isolated bommies, FADs, mooring buoys and anchored boats in blue water. A strong, dirty fighter that buries you in the reef given half a chance, and one of the better-eating pelagics on the coast.
Overview
Cobia are a curious, structure-loving pelagic found from Kalbarri north along the entire WA coast, with the best fishing through the Gascoyne, Pilbara, and Kimberley. They have the silhouette of a small shark or remora and often cruise solo or in pairs around isolated bommies, anchored boats, FADs, and mooring buoys. They're not a fast schooling fish like mackerel — they're an investigator, and a slow-presented bait or jig dropped into their world usually gets eaten. Once hooked, they fight hard and dirty, repeatedly trying to wrap the line on whatever structure they were holding on.
Identification
Black kingfish, crab-eater, lemonfish, sergeant fish
Long and cylindrical with a broad flat head and a protruding lower jaw, dark chocolate-brown to near-black on top with a paler belly and a broad dark stripe down the flank bordered by lighter bands. The first dorsal is a row of short separate spines rather than a fin, which is diagnostic once you know to look. Half the people who see their first cobia call shark or giant remora — remoras carry the ridged sucker plate on top of the head and are much smaller, and a shark has visible gill slits and a vertical tail. Juveniles are strongly banded black and white.
How to Catch
Live mullet, live yakkas, whole pilchards, squid, fresh fish strip
Large soft plastics (7–9 inch jerkshads), slow-pitch jigs, vertical jigs, popping lures over shallow bommies
Heavy spin or overhead outfit with 30–50lb braid and a 60–80lb fluorocarbon leader. A running sinker or no-sinker rig with a 7/0–9/0 circle hook for live and dead baits. For jigs and plastics, a heavy assist rig — cobia inhale lures and a single hook through the head holds best.
When you mark a bommie or pass an anchored boat, give it a wide drift first and watch for cobia cruising in the shadow. Drop a live bait or pitch a soft plastic ahead of the fish — they'll usually swim over to investigate. On the strike, lock up immediately and pull them away from structure or you'll lose them. They're notorious for one or two long, low runs before they sound, so don't relax until the leader is in hand.
Cobia bite year-round in northern WA but are more active through the warmer months from October to April. Slack tide and tide changes around isolated structure produce best. Bright, sunny days actually help — easier to spot fish cruising the shadow line of a bommie.
Up to 60kg, commonly 8–25kg
Year-round (north of Kalbarri)
Size & Growth
Commonly 8–25kg through northern WA, with anything past 30kg a very good fish and the biggest running well beyond 50kg. They grow fast, females outgrow males and reach a larger maximum, and they are reasonably long-lived. The 75cm legal length is a modest fish by cobia standards — most of what turns up on a bommie is comfortably over it. Size varies more with where you are than when: the Gascoyne and Pilbara turn up the big solitary fish, while the smaller ones tend to come in pairs and threes off shallower structure.
Diet & Habitat
Crabs first — the name crab-eater is earned — then prawns, squid, small reef fish and whatever baitfish are around. Cobia are investigators rather than school hunters, cruising isolated bommies, FADs, mooring buoys, wrecks and anchored boats, and they will shadow rays, sharks and turtles to pick up what gets stirred off the bottom. WA range runs from around Kalbarri north through the Gascoyne, Pilbara and Kimberley, with strays picked up further south in warm summers. Anywhere with isolated structure in blue water is worth a drift.
WA Size & Bag Limits
| Minimum size | 75 cm |
|---|---|
| Bag limit | 3 (no separate cobia sub-limit) |
| Counts toward | Counts within WA's large pelagic finfish total mixed bag of 3 per fisher statewide, so up to 3 cobia is legal if they are your only large pelagics for the day. A Recreational Fishing from Boat Licence is required when fishing from a powered boat. |
Minimum size: 750mm. Cobia sit within WA's large pelagic finfish total mixed bag of 3 per fisher (statewide) — there is no separate individual cobia sub-limit, so up to 3 cobia is legal if they're your only large pelagics for the day. A Recreational Fishing from Boat Licence (RFBL) is required when fishing from a powered boat.
Eating Quality
Yes — cobia are excellent eating and arguably the best of the WA pelagics. Firm, white, mild flesh with real thickness off the fillet, and genuinely sashimi-grade when bled at the gills and iced straight away. Skin it, cut thick steaks and pan-sear or grill them; smaller fish crumb up beautifully and the thickness means you can cook it like a piece of meat rather than a fillet. The one thing that ruins cobia is heat before ice — quality drops fast in the north and a fish left on the deck goes soft and loses its sashimi claim within the hour. Big fish over about 25kg get coarser through the shoulder but the belly flap and the tail section still eat well. Cobia freezes better than most pelagics thanks to the low oil content; vacuum-sealed steaks hold for a couple of months without going off.
Perth Tips
Always carry a pitch rod ready when working bommies — cobia appear and disappear quickly and you don't want to be re-rigging. A wide-gape gaff is better than a net for fish over 15kg. Bleed and ice immediately; flesh quality drops fast in the heat. Keep an eye on mooring buoys around Coral Bay, Exmouth, and Onslow on the run home — cobia hold on them more often than people realise.