Mandarin dragonets are distinctive due to their unusual shape and intense coloration. They have a broad, depressed head and are primarily blue with orange, red, and yellow wavy. Males are Mandarin fish lack scales and instead have a thick mucus coating that has an unpleasant smell.
They are found in the western Pacific including the Philippines, Indonesia, Hong Kong, Australia, and New Guinea. Mandarins are found on coral reefs and shallow lagoons and like to remain hidden.
Mandarin fish feed on the bottom and constantly graze for food. They eat small crustaceans such as amphipods and isopods, small worms and protozoans. Much of its food intake is found living in the reefs.
Spawning occurs in areas of the reef where small groups of males and females gather during the night. Mating occurs when the male and the female release sperm and eggs after they align themselves and rise about a meter above the reef. Each female spawns only once each night and may go without spawning for a few days. Since there are few active females, there is much competition among the males. The larger and stronger males tend to mate more frequently because there seems to be a sexual preference by the females for larger males.
Mandarins secrete a mucous that has an unpleasant smell and a bitter taste. They also have a layer of cells on the skin which produce and release substances with some toxins. It is suggested that this secretion is used as a repellent from predators and other competitive fish. The intense coloration also might play a role in avoiding predation by signaling to potential predators that they are toxic. Predatory fish such as the Scorpion fish have been known to feed on Mandarins.