Hippo Tang

The unmistakable "Dory" of the reef — an electric-blue, black-marked surgeonfish that is one of the most recognisable marine fish in the world. It is a peaceful open-water swimmer that darts into the rockwork and wedges itself flat when startled, but it grows to a genuine 30 cm and needs a long, tall tank with real swimming room. Its beauty comes with a catch: it is exceptionally prone to ich and lateral-line disease, so strict quarantine and stable water are non-negotiable.