Chrysiptera notialis
Small blue-and-yellow damselfish logged around North Island, New Zealand, in cool 17-24C water, year-round and easy to miss.
A small, deep-bodied damselfish that tops out around 6 cm, so easy to overlook against rock and kelp backdrops. Look for a blue-toned body with a contrasting yellowish tail and rear fins, the classic damselfish silhouette: oval, laterally flattened, with a single continuous dorsal fin. It holds close to structure rather than swimming in the open, which is often the first clue you have found one.
Divers generally log this one hovering near rocky reef structure or ledges rather than out in open water, sticking fairly close to a home patch. It is not a fish that rushes divers or puts on a show, and sightings are logged as uncommon to rare, so it rewards a slower look into cracks and reef nooks rather than a swim-by glance.
Like other damselfish, it likely holds a small territory around a patch of reef, which is why divers tend to find the same individual in roughly the same spot on repeat dives at a site.
No clear seasonal pattern shows up in the sightings, and the recorded temperature range of 17.1 to 23.9C spans a good chunk of the year in its temperate-to-subtropical range, so treat it as a year-round find rather than a seasonal special.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most consistently logged around North Island, New Zealand, where it turns up at the majority of its known sites. Smaller, more occasional records come from New South Wales in Australia and from Norfolk Island, so those are worth checking but less reliable bets than the North Island sites.
Mapping where Southern Demoiselle is logged…
North Island, New Zealand is the most reliable region, with additional but sparser records from New South Wales, Australia, and Norfolk Island.
There is no strong season in the sighting data, and the 17 to 24C temperature range it tolerates covers much of the year, so it is best treated as a year-round sighting rather than tied to a specific month.
Look for a small, roughly 6 cm damselfish with a blue body and a yellowish tail, holding close to rocky reef structure rather than swimming in open water. Its oval, flattened shape and single dorsal fin are typical damselfish traits.
They reach around 6 cm, making them one of the smaller reef fish you will spot at these sites and easy to swim past if you are not looking closely.
No, they pose no danger to divers and simply hold near their patch of reef as you pass.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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