Optivus elongatus
A small, uncommon reef fish found off New Zealand's North Island, in water between 16.6 and 23.2 C, year-round.
Small and slender-bodied, growing to only about 8 cm, with an elongated profile that sets it apart from the typically deep-bodied roughies. Look for a slim, tapering shape and rough-edged scales catching the light close to rocky structure. It's easy to miss given its size and low-key colouring, so a slow scan of ledges and crevices pays off.
Divers log this one as an uncommon to rare find, usually tucked close to reef structure rather than out in open water. Its small size and low-contrast colouring mean it likely goes unnoticed more often than it's actually absent, so a careful, unhurried look along rock crevices and ledges is the way to find it.
It belongs to the roughy family (Trachichthyidae), a group better known for its deep-water members, making this small, shallower-diving relative something of an outlier worth pointing your torch at.
Sightings don't show a clear seasonal pattern, so treat it as a year-round possibility. Its recorded temperature range of 16.6 to 23.2 C spans much of the North Island's diveable season, which likely explains the lack of a sharp peak.
Every logged sighting so far comes from New Zealand, with North Island sites on the North Island doing the heavy lifting. If you're diving temperate rocky reefs around the North Island, this is where divers have actually found it.
Mapping where Slender Roughy is logged…
All current sightings are from New Zealand, concentrated around the North Island. It's the only region with a confirmed diver record for this species so far.
There's no strong seasonal pattern in the sightings, so it's considered a year-round species. It's been recorded in water from 16.6 to 23.2 C, a range that covers much of the North Island diving calendar.
Look for a small, slender, elongated fish around 8 cm long, resting near rocky reef structure rather than swimming in open water. Its slim profile is the main giveaway compared to bulkier reef fish nearby.
They're small, reaching only about 8 cm in length, so patience and a close look at reef crevices help when searching for one.
They're logged as uncommon at most sites where they've been recorded, and rare at several others. That makes a sighting a real highlight rather than a guaranteed find on any given dive.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Soldierfish
3,621 sites
