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.

The Mandarinfish was first described as Callionymus splendidus in 1927 by Albert William Herre, an American ichthyologist working in the Philippines. It was later placed in genus Synchiropus. The generic name Synchiropus is from Ancient Greek syn-, meaning "together", and -chiropus meaning "hand-foot". The specific epithet splendidus is from Latin for splendid. 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.

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.

Clownfish or anemonefish are fishes from the subfamily Amphiprioninae in the family Pomacentridae. Thirty species are recognized, one in the genus Premnas, while the remaining are in the genus Amphiprion. In the wild they all form symbiotic mutualisms with sea anemones. Depending on species, clownfish are overall yellow, orange, reddish or blackish, and many show white bars or patches. The largest can reach a length of 18 centimetres (7.1 in), while the smallest barely can reach 10 centimetres (3.9 in).

Clownfish are native to warmer waters of the Indian and Pacific oceans, including the Great Barrier Reef and the Red Sea. While most species have restricted distributions, others are widespread. Clownfish live at the bottom of the sea in sheltered reefs or in shallow lagoons. There are no clownfish in the Atlantic.

Clownfish feed on small invertebrates which otherwise potentially could harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. Clownfish are omnivorous: in the wild they eat live food such as algae, plankton, mollusks, and crustacea; in captivity they can survive on live food, fish flakes, and fish pellets. Algae accounts for around 20 to 25 percent of its diet in the wild (and should also account for its amount of algae diet in captivity as well). The diet of the clownfish also consists of copepods, mysids, isopods, zooplankton and undigested food from their host anemones.