Grey mackerel
Scomberomorus semifasciatus
Illustration: Bloom by Day
A dark blue-grey mackerel that is almost unmarked once it is over 70 cm, which is itself the mark — the other mackerels keep their bars, blotches or spots. It schools in turbid inshore water, which is where it is usually met.
how to recognise it
- almost plain once over 70 cm — little or no pattern at all
- dark bluish-grey to iridescent bluish-green above, silvery-white on the sides and below
- small fish under about 10 cm have up to 20 vertical bands above the lateral line, which fade or break into spots as they grow
don’t confuse with
- Spanish mackerel — the Spanish mackerel keeps wavy grey bars as an adult
- Spotted mackerel — spotted mackerel keeps rows of round spots as an adult
- School mackerel — school mackerel keeps large grey blotches as an adult
- Shark mackerel — the shark mackerel has two lateral lines
Field marks read from Fishes of Australia, 2026-10-15. Our wording, their facts. Max size 120 cm FL; 10 kg.
facts
- habitat
- pelagic
- size
- ~80 cm, to 120 cm
Max size from Fishes of Australia (120 cm FL; 10 kg); the typical size is Bluebird’s, not from a cited source
- records
- 28 at 12 spot(s), none of
them in this region
Recorded at Hinchinbrook Island — Ramsay Bay, Magnetic Island — Geoffrey Bay, Hayman Island — Blue Pearl Bay, Hook Island — Manta Ray Bay, Tongue Bay (Whitsunday — North), Cid Harbour (Whitsunday — West), Pioneer Rocks (Whitsundays), Fraser Island — 75-Mile Beach, Fraser Island — Kingfisher Bay (West), Jew Shoal (Sunshine Coast), Redcliffe Jetty, Dunwich Jetty (N Stradbroke — Bay). A count of occurrence records, not abundance. Records are where someone looked.
when it has been recorded
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A gap means no record in the sample, not absence.
the rule
QLD — Min: 60cm · Limit: 5
source
· verified 2026-10-10
no NSW rule listed — check before you dive
no closed season recorded for this species — that is not the same as open; check the official page
Rules checked 2026-10-13 against qld.gov.au
Rules change. Check before you dive.
Occurrence data: Atlas of Living Australia (ala.org.au), CC-BY 4.0.
Diver transect counts: Reef Life Survey (reeflifesurvey.com), CC-BY 4.0, supplied via ALA.
Target and protected species: Queensland tidal-water size and possession limits (qld.gov.au) and NSW saltwater bag and size limits plus threatened species lists (dpird.nsw.gov.au).
Habitat and size: Bluebird, approximate, from general knowledge. Not cited. FishBase is CC BY-NC and this app is commercial, so it is not used.
Description written for Bloom. RECORDS ARE WHERE SOMEONE LOOKED, NOT WHERE THE FISH ARE. A record count is a count of records near here and nothing else -- it is not abundance, and a species with few records is not rare. Absence of records is not absence of fish.
Diver transect counts: Reef Life Survey (reeflifesurvey.com), CC-BY 4.0, supplied via ALA.
Target and protected species: Queensland tidal-water size and possession limits (qld.gov.au) and NSW saltwater bag and size limits plus threatened species lists (dpird.nsw.gov.au).
Habitat and size: Bluebird, approximate, from general knowledge. Not cited. FishBase is CC BY-NC and this app is commercial, so it is not used.
Description written for Bloom. RECORDS ARE WHERE SOMEONE LOOKED, NOT WHERE THE FISH ARE. A record count is a count of records near here and nothing else -- it is not abundance, and a species with few records is not rare. Absence of records is not absence of fish.