Zebrasoma

Zebrasoma is a genus of marine fish composed of seven species of pointed-snout, disc-like bodied, sail-like finned, single peduncular-spined fishes. Zebrasoma are usually placid community fish, many forming large groups or shoals, although fiercely territorial against other tangs or similar shaped or coloured fish in an aquarium setting. Zebrasoma like all Acanthuridae have a forward-facing spine on each side of the caudal peduncle (visible as a short, horizontal stripe on the base of the tail in the above picture). This spine, apart from terminating in a point, has angular edges that result in a scalpel-like sharpness along its length also. When alarmed, tangs can erect the spines sideways and slash at their opponent with rapid sideways movements of the tail. In some surgeons, the spines are fixed in the offensive position. The family name reflects this nature, meaning, literally, "Thorn Tail".