Three-Spot Domino Damselfish

The Three-Spot Domino Damselfish (Dascyllus trimaculatus), also called the Domino Damselfish, is a small, deep-bodied reef fish in the family Pomacentridae, widely distributed across coral reefs of the Indo-Pacific from East Africa to French Polynesia. It is named for the three bold white spots, one on the forehead and one on each side, that contrast sharply against its jet-black to dark brown body, especially in juveniles. Young individuals are frequently found living in close association with sea anemones, a behavior reminiscent of clownfish, before shifting to a more general reef-dwelling lifestyle as adults. It is one of the most recognizable and commonly encountered small reef fish across its wide Indo-Pacific range.

The Three-Spot Domino Damselfish has a distinctive black-and-white pattern that changes somewhat with age.

• Deep, oval, laterally compressed body typical of the genus Dascyllus
• Jet-black to dark brown base coloration
• One prominent round white spot on the forehead and one on each side of the body, forming the 'three spots'
• Spots are bolder and more contrasting in juveniles, fading somewhat in larger adults
• Small mouth and rounded fins
• Grows to about 8-14 cm The combination of solid black body and three symmetrical white spots reliably separates it from other Dascyllus damselfish, most of which have additional bars or different spot placement.

Three-Spot Domino Damselfish are found across coral reefs of the Indo-Pacific, from the Red Sea and East Africa to Southeast Asia, Australia, and as far as French Polynesia. They typically inhabit shallow to moderate reef depths of roughly 1 to 55 meters, often near coral heads, rubble patches, and sheltered lagoons. Juveniles commonly associate closely with sea anemones or branching corals for protection, while adults move more freely across open reef areas and rubble zones, forming loose aggregations around prominent coral structures.

Three-Spot Domino Damselfish are social, often forming small to large aggregations around a shared coral head or reef structure, particularly as juveniles sheltering near anemones. Adults become more territorial, defending favored feeding or shelter sites against intruders. They are omnivorous, feeding on plankton picked from the water column as well as small invertebrates and algae from the reef surface. During spawning, males prepare and guard a nest site on the reef, attracting females to lay adhesive eggs that the male then fans and defends until hatching. Their abundance and site fidelity make them an ecologically important and frequently observed component of Indo-Pacific reef communities.