Cobia and queenfish in Thai waters: the mid-water surprise species

Neither cobia nor queenfish show up on most Thai spearo bucket lists, but both are landed regularly by hunters who keep their guns up in mid-water. They occupy the same ecological layer, respond to similar structures, and reward the same technique: the spearo who stays loaded, scans mid-column, and shoots without hesitation.

This is the practical guide.

The short version

• Cobia: 3-15 kg typical. Associates with structure — buoys, anchor lines, FADs. Curious, often comes right to the spearo.
• Queenfish: 1-6 kg typical. Nomadic mid-water schooler. Moves fast, bright silver, feeds on baitfish clouds.
• Shared habitat: 5-20 m depth, mid-water column, current-exposed reefs.
• Right gun: 90 cm Snapper Railgun, single 14 mm or double 14 mm, 7 mm shaft with flopper. Same setup handles both.
• Both coasts: Gulf and Andaman hold productive populations. Gulf is more consistent for numbers.

Cobia — the curious predator

Cobia (ปลาช่อน-ทะเล, Rachycentron canadum) are bronze-grey, torpedo-shaped, and often mistaken for small sharks on first glance. They are remora’s larger cousin — a solitary fish that associates with structure and follows larger animals out of curiosity.

Where cobia show up

• Mooring buoys — a spearo classic. Cobia hang under mooring buoys on open water, 5-15 m depth, waiting for passing food. A dive on an offshore mooring often produces a cobia encounter.
• FADs (Fish Aggregating Devices) — anchored floating structures that attract fish. Cobia often hang under or beside them.
• Sunken structure — wrecks, old boats, anchor blocks. Cobia cruise the edges.
• Larger marine life — cobia sometimes follow whale sharks, manta rays, and even large reef sharks. If you see a larger animal pass, scan behind it.

Technique for cobia

Cobia are not spooky. They are curious. This is rare among gamefish and you should exploit it:

1. Descend quietly to the structure’s depth. Not deeper — cobia generally hold in the upper-mid column.
2. Settle against the structure or just below the buoy. Still, gun up, scanning.
3. If a cobia is there, it will often come to you. They circle in for a look, giving you a clean shot at 2-4 m range.
4. Shoot behind the pectoral fin through the spine. Their skull is hard — side-spine shots kill cleanly.

Gear for cobia

A 90 cm Snapper Railgun with single 14 mm is ideal. You want enough power for a 10 kg fish but not the bulk of a bluewater gun. 7 mm shaft with flopper is standard.

Reel is optional at under 5 kg class. Float + 20 m line is essential above 8 kg because a shot cobia can run hard.

Queenfish — the speed hunter

Queenfish (ปลาสาก, Scomberoides lysan, S. commersonnianus) are flashy silver mid-water schoolers. They feed on baitfish — sprats, anchovies, small fusiliers — and appear in fast, tight schools when bait is concentrated.

Where queenfish show up

• Current lines — visible edges where two water masses meet.
• Baitfish concentrations — if you see a tight cloud of sprats or fry, queenfish may be underneath.
• Shallow reef edges in early morning — 3-8 m depth, high activity at dawn.
• Offshore pinnacles at 8-15 m — secondary but consistent habitat.

Technique for queenfish

Queenfish are fast. You don’t approach them — you intercept.

1. Identify a baitfish concentration and position down-current or below it.
2. Descend to the queenfish cruising depth (usually 3-8 m) and freeze.
3. When the school arrives, pick one fish on the edge. Never shoot into the middle of a school — you either miss or foul-shoot.
4. Lead the fish — queenfish move faster than reef species. A 15-20° lead at 4 m range is normal.
5. Shoot through the side, behind the gill plate. Spine shot preferred.

Gear for queenfish

Same 90 cm Snapper setup as cobia. Queenfish bodies are thin — a 14 mm rubber with 7 mm shaft is plenty of penetration. Avoid over-gunning — you want a fast-reloading setup because queenfish encounters are often multi-fish opportunities.

The 90 cm Snapper as the mid-water workhorse

For a single-gun Thai spearo covering reef + mid-water species, a 90 cm Snapper Railgun is the correct choice. Reasons:

• Range: effective to 4-5 m, which covers queenfish intercept distance.
• Power: single 14 mm handles 10 kg fish cleanly.
• Reload speed: single-band loads fast on the surface.
• Versatility: also covers hole-hunting grouper and snapper (see our snapper hole-hunting guide and grouper guide).

If you’re new to spearfishing and don’t know what to buy first, the 90 cm Snapper is the right default. The All-Round Hunter Kit bundle pairs it with the mask, fins, belt, float, line, and reel to handle mid-water and reef simultaneously, at 14% off.

Shot placement — a comparison

Species	Best shot	Avoid
Cobia	Behind pectoral, through spine	Head-on (dense skull)
Queenfish	Side, through gill plate, lead slightly	Tail (thin, tears)

Both species respond well to spine shots. Neither has the bone density of a large tuna or the fight of a GT — precision placement makes the fight short.

Seasonal timing

Both species are year-round residents in Thai water. Peak activity:

• Cobia: December-March on both coasts. Lower activity during monsoon.
• Queenfish: October-April Gulf, November-April Andaman. Schooling is most predictable in dry-season clear water.

Skip July-September on the Andaman (monsoon). Full calendar: Thailand spearfishing season.

Where to hunt legally

Both species are available on legal Thai coast:

• Gulf mainland (Chumphon, Prachuap) — good queenfish on current edges.
• Koh Samui outside Ang Thong — cobia on moorings, queenfish on baitfish.
• Southern Phuket outside park zones — both species on offshore current lines.
• Krabi mainland outside Hong park — mixed mid-water opportunities.

Full legality breakdown: Legality and marine parks.

Training

Cobia and queenfish are good intermediate targets. Requirements:

• Apnea Total Level 1 complete.
• Comfortable at 10 m depth.
• Static PB 2:00+ dry.
• Basic reef hunting experience before attempting mid-water ambush.

Use our breath-hold trainer to push your PB before stepping up to these species.

Eating note

Cobia is excellent eating — firm, white flesh, often compared to cobia-sashimi quality in fine restaurants. Best grilled with olive oil and salt, or as ceviche if landed fresh.

Queenfish is softer-fleshed, best eaten within 24 hours. Traditional Thai preparation is pla salad — deep-fried crispy with sweet chilli sauce.

Both require ikijime dispatch at the boat — the flesh improves dramatically with proper brain-spike bleed-out over a slow death.

One practical note

Keep your gun up and loaded in mid-water. Most cobia and queenfish shots are missed not because of poor aim but because the spearo had the gun pointed down scanning the bottom when the fish arrived from mid-column. Scanning behaviour matters as much as shooting skill.

Got questions about gun choice for mid-water work? WhatsApp me with your typical dive profile and target species — I’ll tell you whether the 90 cm Snapper is right for you or if you’d be better with something else.