Synchiropus splendidus
Mandarin-fish
(Also: Mandarinfish)

Synchiropus splendidus is found in much of the western Pacific including the Philippines, Indonesia, Hong Kong, Australia, and New Guinea (Delbeek, 1989). These fish are also found in the Ryukyu Islands (Randall et al. 1990). Outside of its native range, S. splendidus is primarly a marine aquarium fish (Sandovy et al. 2001). (Delbeek, 1989; Randall, et al., 1990; Sadovy, et al., 2001)

Mandarin fish are tropical, marine fish found in waters with a temperature range of 24 to 26ºC. They are bottom dwelling, found at depths up to 18 m (Randall et al. 1990). During spawning they are pelagic and are seen in the open ocean (Sadovy et al, 2001). Mandarin fish are found on coral reefs and shallow lagoons hidden under foliose and dead coral (Randall et al. 1990). It is difficult to maintain mandarin fish in captivity because of their dietary requirements (Sadovy et al, 2001). (Randall, et al., 1990; Sadovy, et al., 2001)

Mandarin fish 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 lines (Delbeek 1989). Mandarin fish are small, reaching a maximum length of 6 cm. Males are notably larger than females (Sadovy et al. 2001). Mandarin fish lack scales and instead have a thick mucus coating that has an unpleasant smell (Sandovy et al. 2005). They have 4 dorsal spines, 8 dorsal soft rays, and no anal spines. In males, the first dorsal spine is greatly elongated, sometimes long enough to reach the caudal peduncle (Delbeek 1989). (Delbeek, 1989; Sadovy, et al., 2001; Sadovy, et al., 2004)

Mandarin fish have a short incubation time and larvae that are small and develop quickly. Clutch sizes range from 12 to 205. Eggs measure from 0.7 to 0.8 mm in diameter, are colorless, spherical, and pelagic. The eggs at first are clumped together and then slowly break up into smaller units. The eyes become pigmented and the mouth becomes well developed 36 hours after fertilization. During the flexion stage, which occurs after 8 to 11 days, the caudal fins become distinctive, the pelvic fin rays move distally and the body becomes robust. The larvae are active and feeding at this stage. After 12 to 14 days, which is the settlement stage, juveniles look like the adults with a large head,and a triangular shaped body. In 18 to 21 days, the body darkens to an orange brown color with greenish banding and the dorsal spines are observed. The adult color pattern does not develop until the second month when lengths are from 10 to 15 mm. The swim bladder is retained in adults (Sadovy et al. 2001). (Sadovy, et al., 2004)

Spawning occurs on 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 amoung 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 (Sadovy, 2001). (Sadovy, 2001)

Mandarin fish are pelagic spawners. External fertilization occurs when a male and female are in close contact and swimming upward. Spawning occurs at about weekly intervals where up to 200 eggs are released. This occurs for several months (Delbreek, 1989) Mandarin fish breed year round. The population doubling time is less than 15 months (Randall, 1990). (Delbeek, 1989; Randall, et al., 1990)

Mandarin fish have no parental involvement after release and fertilization of eggs.

In the wild mandarin fish are expected to live between 10 to 15 years (Sale, 2002). In captivity, however the lifespan is greatly reduced due to dietary requirements. On average, mandarin fish live between 2 to 4 years in captivity (Delbeek, 1989). (Delbeek, 1989; Sale, 2002)

Mandarin fish are slow, shy, and mostly passive. They have large fan-like pelvic fins which are used often to walk along the bottom. Mandarin fish are found usually in groups or in pairs on reefs. In captivity, mandarin fish are rather intolerant of conspecifics. Two males will not survive together in an aquarium due to their agressive behavior towards each other (Delbeek 1989). During daylight hours, mandarin fish move along coral branches or hide in their home crevices (Sadovy et al. 2004). (Delbeek, 1989; Sadovy, et al., 2004)

There was no information found pertaining to the home range of mandarin fish.

Mandarin fish secrete mucous that has an unpleasant smell and a bitter taste. They also have a layer of sacciform 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 significance of the vibrant display of colors of the species is not known. However, it probably makes them highly conspicuous when feeding and mating and may be an aposematic warning (Sadovy et al. 2005). (Sadovy, et al., 2004)

Mandarin fish feed on the bottom. They eat small crustaceans such as amphipods and isopods, small worms and protozoans. Much of its food intake is found living in the reefs and other live rock. If there is a substantial amount of live rock, mandarin fish do not need any other outside source for food. In captivity, the fish usually do not eat prepared food, therefore it becomes difficult to maintain them. They need a great supply of live rock to feed. Mandarin fish have a relatively small mouth, therefore they eat only small food items (Delbeek 1989). (Delbeek, 1989)

Mandarin fish secrete mucous which might act to repel predators. The intense coloration also might play a role in avoiding predation by signalling to potential predators that they are toxic (Sadovy et al. 2005). Early development could possibly be an adaptive strategy to reduce the risk of predation (Sadovy et al, 2001). There is no available information on specific predators of the species. (Sadovy, et al., 2001; Sadovy, et al., 2004)

Mandarin fish eat small invertebrates (Sadovy et al. 2004). Beyond this, little is known of the role of mandarin fish in the ecosystem. (Sadovy, et al., 2004)

The vibrant display colors of mandarin fish make them valuable fish for the aquarium trade (Sadovy, 2001). The aquarium trade of mandarin fish plays a part in the local economies of the Phillipines and Hong Kong. These fish are also used as food in many Asian countries (Sadovy, 2001). (Sadovy, 2001; Sadovy, et al., 2001)

There are no known adverse effects of S. splendidus on humans.

Mandarin fish do not have any special conservation status currently (Randall, 1990). (Randall, et al., 1990)