Mandarinfish

S. splendidus is one of only two vertebrate species known to have blue colouring because of cellular pigment, the other being the closely related 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 is structural, as it comes from thin-film interference from piles of flat, thin and reflecting purine crystals.

Based on the gut analyses of seven wild fish Sadovy et al. (2001) determined that the mandarinfish has a mixed diet that consists of harpacticoid copepods, polychaete worms, small gastropods, gammaridean amphipods, fish eggs and ostracods.

In the wild, feeding is continuous during daytime; the fish peck selectively at small prey trapped on coral substrate in a home range of many square meters.

Despite their popularity in the aquarium trade, mandarinfish are considered difficult to keep, as their feeding habits are very specific. Some fish never adapt to aquarium life, refusing to eat anything but live amphipods and copepods (as in the wild); though individuals that do acclimatize to aquarium food are considered to be quite hardy and highly resistant to diseases, such as marine ich. They are less likely to contract marine ich because they do not have the typical skin type that is affected by this disease. Mandarinfish also have a layer of debatably smelly and bitter slime instead of scales, which blocks out disease and probably also discourages predators, implying their bright coloration is aposematic.

The mandarinfish appeared on a 39-kip postage stamp from Laos issued in 1987, and a 40-cent postage stamp of the Federated States of Micronesia issued on 26 August 1993.