Mandarin Dragonet

Fascinating facts about the Mandarin Dragonet

• The mandarinfish is one of just two vertebrate species whose blue hue comes from actual pigment cells, the other being its close relative the psychedelic mandarin. This blue is produced by specialised cyanophores, pigment-containing cells that both hold colour and reflect light. In contrast, virtually all other vertebrates display blue through structural means, using thin-film interference of purine crystals.
• Its oversized pelvic fins act like tiny legs, letting it literally walk across the reef floor, a behaviour that often leads observers to mistake these fins for the pectoral pair. The fins are positioned low on the body and are used to push against the substrate while the true pectoral fins, almost transparent, sit near the centre of the fish.
• Instead of scales, the mandarinfish is coated in a layer of debatably smelly and bitter slime that blocks out disease and probably also discourages predators, making its bright colours a warning signal. This slime contributes to the species' low susceptibility to marine ich, as they lack the typical skin type the parasite attacks. Individuals that do adapt to aquarium life are noted for being unusually hardy and resistant to disease.
• Mandarinfish are far less prone to marine ich because their skin lacks the usual type the parasite attacks, giving them a natural shield against the disease. This protection comes from a thin, bitter slime coating that replaces scales and helps block pathogens. As a result, individuals that do adapt to aquarium life tend to be unusually hardy and show strong resistance to infections, making them prized by hobbyists despite their demanding diet.
• Male mandarinfish display a dorsal fin that is exceptionally tall compared with the rest of their body, creating a striking silhouette on the reef. The fin is richly coloured with vivid orange and blue patterns that complement the fish's overall flamboyance. This pronounced fin, positioned near the centre of the back, is a distinctive feature of the species and contributes to its reputation as one of the most colourful reef dwellers.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia

At a glance

About the Mandarin Dragonet

The Mandarin Dragonet (Synchiropus splendidus), often called the mandarinfish, is among the most extraordinarily coloured animals in the sea, a palette of electric blue, orange and green swirled into psychedelic, maze-like patterns across its tiny body. Native to the warm inshore reefs of the western Pacific, from Japan's Ryukyu Islands south to Australia, it lives a secretive life among coral rubble and the branches of sheltered lagoons, rarely straying into open water. A member of the dragonet family, it moves with a slow, almost insect-like hover, propelled by constantly fanning pectoral fins as it picks tiny crustaceans from the reef. Despite its dazzling appearance it is shy and easily overlooked, emerging most visibly at dusk for its remarkable courtship, and its beauty has made it one of the most coveted, and most difficult to keep, fish in the marine aquarium trade.

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