The Mandarinfish or Mandarin dragonet (Synchiropus splendidus), is a small, brightly colored member of the dragonet family, which is popular in the saltwater aquarium trade. The mandarinfish is native to the Pacific, ranging approximately from the Ryukyu Islands south to Australia. It was later placed in genus Synchiropus. The common name of the Mandarinfish comes from its extremely vivid colouration, evoking the robes of an Imperial Chinese mandarin. Other common names include Mandarin goby, Green mandarin, Striped mandarinfish, Striped dragonet, Green dragonet and sometimes Psychedelic mandarinfish. The similarly named mandarin fish (Siniperca chuatsi), properly known as the Chinese perch, is only distantly related.
The Mandarinfish belongs to the perciform family Callionymidae, the dragonets, which counts 10 genera and more than 182 species. Genus Synchiropus counts 51 species, divided into 10 subgenera. The Mandarinfish is in subgenus Synchiropus (Pterosynchiropus) along with the Australian LSD-fish (S. occidentalis) and the LSD- or psychedelic fish (S. picturatus).
To date, S. splendidus is one of only two animal species known to have blue colouring because of cellular pigment, the other being the closely related LSD-fish Psychedelic Mandarin (S. picturatus). The name “cyanophore” was proposed for the blue chromatophores, or pigment-containing and light-reflecting cells. In all other known cases, the colour blue comes from thin-film interference from piles of flat, thin and reflecting purine crystals.
Mandarinfish are reef dwellers, preferring sheltered lagoons and inshore reefs. While they are slow-moving and fairly common within their range, they are not easily seen due to their bottom-feeding habit and their small size (reaching only about 6 cm). They feed primarily on small crustaceans and other invertebrates.