Card #072 · Fish
Mandarinfish
Synchiropus splendidus
Common LC · Least Concern
Field notes
- Classification
- Order Syngnathiformes · Family Callionymidae
- Range
- Western Pacific coral reefs
- Size
- ~6 cm (2.4 in)
- Weight
- ~2 g (0.07 oz)
- Lifespan
- ~2–4 yrs
- Diet
- Copepods, small crustaceans
Most Notable
Almost every blue animal is a trick of the light, colour thrown by stacked crystals. This one has actual blue pigment, in cells named cyanophores, and only one other vertebrate is known to share it.
It has no scales at all. In their place is a thick layer of mucus, bitter and rank enough that most things spit it out, which does the work armour would do elsewhere and doubles as a barrier against infection. The colour on top is a warning, not decoration.
The other vertebrate known to carry true blue pigment cells is its close relative the psychedelic mandarin, Synchiropus picturatus. Everything else with a backbone, from a blue jay to a blue whale, is faking it with structure.
A mandarinfish spends the day picking tiny crustaceans one at a time off the reef, mostly copepods. That habit is exactly why it is a hard aquarium fish: many refuse anything that is not alive and moving, and quietly starve in tanks that cannot supply them.
For all the colour, it is small and cryptic, staying low in rubble and coral on sheltered inshore reefs rather than out in open water.
Range: Sheltered reefs and lagoons of the western Pacific.