Microspathodon bairdii
Track down this chunky Pacific damselfish on reefs from Mexico's Pacific coast to the Galápagos, year-round in 23 to 29C water.
Recognisable by its stocky, deep-bodied shape and blunt, rounded forehead, which gives it a noticeably bulkier profile than most damselfish. Adults run a dull grey-blue to brownish colour, often with a faint pale mottling, and grow to around 18cm, large for the family. The steep head profile and thickset body are the quickest cues underwater, especially when it is hovering close to rock or reef structure rather than darting in open water.
Usually spotted hovering solo or in loose company near rocky reef and boulder terrain rather than schooling in open water. It tends to hold its ground over a patch of reef, sometimes tending algae growth on the rock, and doesn't scatter readily when divers approach slowly. Most logs describe it as uncommon rather than abundant, so it's the kind of fish you notice while working a reef wall rather than something that swarms a site.
Like other damselfish, it likely defends a patch of algae-covered rock as a feeding territory, which is why divers often find the same individual holding station over one spot on repeat dives.
No clear seasonal pattern shows up in sightings, and with a comfortable range of roughly 23 to 29C, it turns up on these Pacific reefs throughout the year.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably found along the Pacific coast of Mexico, with strong numbers also logged around the Galápagos Islands in Ecuador and the Pacific coast of Panama. Costa Rica's Central Pacific also turns up regular sightings, with a smaller cluster of records from Baja California.
Mapping where Bumphead Damselfish is logged…
Best logged along Mexico's Pacific coast, with solid records from the Galápagos Islands in Ecuador, Panama's Pacific coast, and Costa Rica's Central Pacific.
There's no strong season in the sighting data, and it tolerates a wide temperature range of about 23 to 29C, so it's a reasonable find on Pacific reefs any month.
Look for a stocky, deep-bodied damselfish around 18cm with a distinctly blunt, rounded head profile and grey-blue to brownish colouring, usually hovering close to rocky reef structure.
They reach around 18cm, making them one of the bulkier members of the damselfish family rather than the small, slender types most divers picture.
Most dive logs describe it as uncommon, with rare sightings at many sites and only one location reporting it as common, so spotting one is a nice find rather than a given.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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