Like its yellow cousin and a previous title-holder, this week’s Fish of the Week is hugely popular amongst marine aquarists due to its passive nature and pronounced appearance. Until recently, it was thought that the purple tang (Zebrasoma xanthurum), also known as the yellowtail sailfin tang, could only be found in the Red Sea, but specimens have recently been found in the Persian Gulf and the Arabian Sea. As their name suggests, these fish are a vivid purple colour, whilst their anal fin is almost completely yellow. Sometimes their pectoral fins have yellow tips too, and their heads are often covered in tiny black spots. These are relatively large fish, growing to around 25cm (almost 10 inches), and look even bigger when their dorsal and anal fins are fully extended. They are strict herbivores feeding on benthic algae in the wild, so are unlikely to take a chunk out of your corals. They will do best in large tanks with peaceful tank mates and few conspecifics as they can be a little boisterous, but will be sure to add a dash of purple pizazz to any marine setup.