Aplodactylus etheridgii
Uncommon but reliable around North Island, New Zealand, in cool 14.6-23.3C water, year-round with no clear season.
Grows to around 31 cm, with a stocky, deep-bodied shape typical of marblefish and a mottled brown-to-grey pattern that breaks up its outline against rock and kelp. Look for the blunt head profile and the notch-like indent that gives the species its name, most visible when the fish is viewed head-on or from above. It tends to sit low against reef structure rather than swim in open water, which makes the marbled camouflage the easiest first clue.
Divers typically find it holding close to rocky reef and kelp structure rather than out in open water, relying on its mottled colouring to blend in rather than bolting when approached. It is logged as an uncommon sighting even at the sites where it does occur, so patient reef-scanning around ledges and kelp beds pays off more than open-water searching.
It belongs to the marblefish family (Aplodactylidae), a small group of cool-temperate reef fish largely restricted to southern hemisphere coastlines, which is part of why sightings cluster so tightly around New Zealand.
Sightings show no detectable seasonal pattern, and the observed temperature range of 14.6 to 23.3C spans New Zealand's cooler and warmer months alike, so it is logged year-round rather than in a specific season.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most records come from North Island, New Zealand, which accounts for the large majority of logged sites, with a smaller presence around Norfolk Island. If you are targeting this species specifically, New Zealand's North Island reefs are the dependable option.
Mapping where Notchhead Marblefish is logged…
They are most reliably logged around North Island, New Zealand, with a smaller number of sightings near Norfolk Island. New Zealand's North Island is the strongest bet for a targeted search.
There is no clear seasonal pattern in sightings, and they turn up across a wide temperature range from about 14.6 to 23.3C, so year-round diving in North Island, New Zealand gives you a fair shot.
Look for a stocky, deep-bodied fish around 31 cm with mottled brown-grey camouflage sitting close to rocky reef or kelp. The blunt head and characteristic notch near the head are the key features that separate it from similar-looking reef fish.
They typically reach around 31 cm in length, making them a medium-sized reef fish rather than a standout giant or miniature on the reef.
No, they pose no danger to divers. They are a docile, camouflage-reliant reef fish with no venomous spines or aggressive behaviour reported.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Sun Perch
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