Beauty is Skin Deep

It’s almost impossible to mistake the Mandarin Dragonet for any other fish. As one of the most strikingly coloured reef inhabitants in the world, its beauty is the stuff of legend and specimens are highly prized amongst discerning marine-loving aquarists. With its almost psychedelically vivid blue and green body crossed by wavy orange lines and bright red tail with blue edging, it has arguably the most attractive colouration and pattern of any domestically kept reef fish. But one of the most fascinating things about the Mandarin’s colour is that, unlike other fish, its beauty isn’t a trick of the light.

While the oceans are full of a veritable rainbow of brightly-coloured inhabitants, the amazing hues on display are not in fact a part of the fish themselves but are actually due to the physics of reflection. As the great majority of reef fish are scaled, the colours that they display are actually the result of the way in which light reflects off thin, flat crystals in their scales. The Mandarin is scale-less, however, meaning that it can’t pull off this particular trick to look its best and instead goes for the direct and honest approach, packing millions of microscopic pigment-containing cells into its skin. Called chromatophores, the cells mean that what you see is literally what you get and that the Mandarin’s awe-inspiring colours are actually a part of its genetic make-up rather than a trick of the light.

What’s more, the Mandarin is almost completely unique in this ability, sharing its blue cell pigmentation with only one other vertebrate in the known world – the equally vibrant and closely-related Picturesque Dragonet.