Dascyllus trimaculatus is from the order of Perciformes and family of Pomacentridae. It is commonly known as the Threespot humbug. Juveniles have an overall black body, with black blotches on the forehead and on the sides. These colours fades as the fish grow into adults. Their scales have a bluish centre. Adults are more greyish in colour with variable spots or reduced spots or no spots at all. Some individuals possess yellow caudal, anal and pelvic fins. There is a total of 12 to 13 dorsal spines, 18 to 20 dorsal soft rays, 3 anal spines and 15 to 17 anal soft rays.
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This species is present across the Indo-Pacific region. Recorded depth range is between 1 to 55 meters. They can be found in coral and rocky reefs. They are found in small or large groups and are often seen living with anemones. Their diet consists of algae and planktonic crustaceans. Adults form distinct pairs during breeding. Their eggs adhere to the substrate and the males guard them until they hatch.
The conservation status of this species has not been evaluated yet. They form a significant part of the aquarium trade which could potentially harm population stability.
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