Mandarinfish

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The mandarinfish or mandarin dragonet, 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. It can usually be found in some of the warmer waters.
It 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. The mandarinfish has a body shape similar to a goby,
though this is the only resemblance between the two. The vivid coloration sports a
bright blue background, with swirly orange stripes and a blue-greenish face with
bold blue stripes. The large pelvic fins are used for 'walking' on the seafloor and are
often mistakenly seen as the pectoral fins. The real pectorals are located almost at the
center and are nearly transparent, with a tinge of fin, the anal fins and on part of the
tail, the rest of which is striped in vibrant orange and blue. The dorsal fin, which is
exceptionally tall in males, has a striking orange-and blue design as well. The eyes
are usually red with black pupils. Different varieties sport different markings and
colors. The green mandarin is the fish that has been described. The red mandarin is
the same species, but its pelvic fins and what would be orange is red. In some rare
cases, the entire dragonet is red with black stripes. The spotted mandarin is light
gray-green with black, pink and blue spots.

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Mandarinfish are reef dwellers, preferring sheltered lagoons and inshore reefs. While
they are slow-moving and fairly common within their range, they are not easily seen
due to their bottom-feeding habit and their small size (reaching only about 6 cm).
They feed primarily on small crustaceans and other invertebrates.
Based on the gut analyses of seven wild fish 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.