Keyhole Angelfish
Centropyge Tibicen
© 2026 MarineWise
Quick Facts
Distribution
- The Keyhole Angelfish is a deep, almost jet-black fish named for the distinctive white oval patch on its side. That pale marking sits like a keyhole punched through the dark body, making it one of the easier reef fish to pick out at a glance.
- Adults grow to about 18 to 19 cm long, which makes the Keyhole Angelfish the largest species in its group. For a dwarf angelfish, that is a genuinely impressive size.
- In Australia, Keyhole Angelfish are found along the Great Barrier Reef in Queensland and across parts of Western Australia, including the Houtman Abrolhos Islands and Scott Reef. Juveniles sometimes drift as far south as Merimbula on the New South Wales coast.
- The wider range of the Keyhole Angelfish stretches across the Indo-Pacific, from Christmas Island and the Timor Sea through to Fiji and Tonga, and as far north as southern Japan and Taiwan. Lord Howe Island and Norfolk Island are also part of its territory.
- Keyhole Angelfish live on coral and rubble areas of reef lagoons and on the outer slopes of reefs, usually at depths of 4 to 35 m. They stay close to the reef structure, using gaps and ledges for cover.
- This species grazes on algae growing over rocks and coral surfaces. It feeds by picking steadily across the reef, rather than chasing prey through open water.
- Keyhole Angelfish live in small harems, typically one male with two to six females. Adults are often seen in loose groups, while younger fish tend to move around on their own.
- If the male of a harem disappears, the largest female will change sex and take his place. The whole process, including the physical and behavioural shift, takes roughly four to five weeks.
- Young Keyhole Angelfish look noticeably different from adults. Juveniles are mostly black with a clear white vertical bar on the side. As they grow, that bar gradually breaks up into the oval blotch adults carry.
- Look closely at the fins and there are some subtle colour details worth noticing. The lower fins carry a wash of yellow, and a thin blue line runs just inside the edge of the dorsal and tail fins.
- Males defend their territory and perform courtship displays to attract females within the harem. Spawning typically happens in the water column, with eggs released to drift with the current.
- Keyhole Angelfish can live for at least six years, though some may live longer in the wild.
Species Interaction
Keyhole Angelfish: A Reef Jewel in Tanks and on Transects
- Aquarium
- Snorkelling & Diving
- Research & Rare Encounters
- Ecosystem Role
The Keyhole Angelfish is best known to the aquarium trade, where its striking dark body and white oval blotch make it a sought-after species in the commercial marine fish market. Reef divers and snorkellers encounter it across Indo-Pacific reefs, including along the Australian east coast from the Great Barrier Reef south to New South Wales, though it tends to be uncommon rather than abundant. Volunteer divers regularly record it on reef transects, contributing to broader monitoring of reef fish communities.
Scientific Classification
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Acanthuriformes
- Family: Pomacanthidae
- Genus: Centropyge
- Species: Centropyge tibicen
Conservation Status
The Keyhole Angelfish is listed as Least Concern by the IUCN, with a wide Indo-Pacific distribution and no evidence of significant population decline. It holds no threatened status under Australia’s EPBC Act. The species is collected for the aquarium trade but is not a targeted food fish.
Interaction Highlights
Aquarium
Requires a 70-gallon tank and kept with caution on coral reef setups.
Diving
Encountered on lagoon and seaward reefs from the GBR to southern NSW.
Ecosystem
A herbivore grazing algae from reef surfaces within small harem groups.
Keyhole Angelfish
As Aquarium Fish
Care Level: Moderate
Temperament: Semi-Aggressive
Diet: Omnivore
Reef Compatible: With caution
Minimum Tank Size: 70 gallons
Recreational Viewing
- Snorkeling & Scuba
Finding: Difficult
Temperament: Shy
Location: Inner Reef, Outer Reef, Lagoon
Danger: None
