Whitetail Dascyllus

A stocky little damselfish, Dascyllus aruanus wears an unmistakable zebra livery: three vertical black bars across pearly flanks, with the pale tail that earns it its name. It rarely exceeds ten centimetres, most adults settling near six. Like the clownfishes, its relatives in the Pomacentridae, it has a spirited temper. In the wild it haunts shallow reef flats and lagoons of the Pacific, from the surface to about twenty metres, hovering above thickets of staghorn Acropora. Those branching corals are its refuge: the shoal rises as a cloud to pick zooplankton from the current, then pours back in at the first alarm. Its hardiness makes it a fine first marine fish, if the temper is accepted. A 120-litre tank suits a small harem, but adults turn territorial and harry fish far larger than themselves, so add them last, to a rocky aquascape full of retreats. An omnivore, it takes pellets, mysis and spirulina, and spawns freely, the male guarding the eggs. Corals are safe.