Threespot Dascyllus, also called as Domino Damsel or just Domino, is a type of damselfish in the Pomacentridae family.
It lives in the Indo-Pacific region, from the Red Sea and East Africa to places like Japan, Australia, and the Philippines.
Threespot Dascyllus eat algae and small crustaceans like copepods that live in plankton.
It lives around coral reefs and rocky areas as adults. Young fish often stay close to large sea anemones, sea urchins, or small corals for protection.
Threespot Dascyllus usually form groups of different sizes. This fish is active during daylight hours (diurnal) and is reef-safe.
Threespot Dascyllus Interesting Facts
- Threespot Dascyllus have a unique domino-like pattern with two white spots on their sides and one between their eyes.
- They are reef-safe fish that live in coral reefs, feeding primarily on algae and small crustaceans like copepods.
- Males protect the eggs by providing air and guarding them until they hatch.
- Recent research debunks the belief that they can change gender; instead, they exhibit non-functional hermaphroditism.
Threespot Dascyllus Habitat
Threespot Dascyllus is a marine fish found in the Indo-Pacific region, ranging from the Red Sea and East Africa to the Line and Pitcairn Islands.
It also lives as far north as southern Japan and as far south as Sydney, Australia. However, it’s not present in Hawaii or the Marquesan Islands.
This fish prefers marine habitats like coral reefs and doesn’t migrate. It can be found at depths of 1 meter (3 feet) to 55 meters (180 feet).
Threespot Dascyllus thrives in tropical waters with latitudes between 32°N to 36°S, and longitudes from 24°E to 128°W.
Threespot Dascyllus Physical Characteristics
Size: 5.5 inches (14.0 centimeters)
Threespot Dascyllus grows up to 5.5 inches (14.0 centimeters) long and weighs around 45.21 grams.
It has 12 dorsal spines, 14 to 16 dorsal soft rays, 2 anal spines, and 14 to 15 anal soft rays.
This fish has a grey or black body with two white spots on its sides and one between its eyes.
This pattern looks like a domino piece, which is why it’s called “Domino.”
Young Threespot Dascyllus fish have a mostly black body with blue scale centers, a white forehead blotch, and upper side spots.
Their fins are black except for the transparent pectoral fin and the outer part of the soft dorsal rays.
Adults’ colors vary based on location and behavior. They don’t have forehead spots; their upper side spots are smaller; their head and fins are usually black; their scales have black edges.
The edges of some facial bones are finely serrated. During mating season, they generally appear paler.
Their body depth is about 1.4 to 1.6 times shorter than their standard length.
Threespot Dascyllus Reproduction
Threespot Dascyllus lay eggs, and they form specific pairs when breeding. The eggs stick to surfaces in the water.
Male fish protect and provide air for the eggs. During courtship, males perform a “signal-jumping” behavior.
In captivity, a pair of these fish were observed to spawn three times a month, totaling 17 times over seven months.
Although it was once thought that this species could change from female to male (protogyny), recent research shows that they have both male and female traits but don’t actually change gender (non-functional hermaphroditism).