With their bright colours and deep, laterally compressed bodies, marine angelfishes are some of the more conspicuous residents of the reef. They most closely resemble the butterflyfishes, a related family of similarly showy reef fish. Marine angelfish are distinguished from butterflyfish by the presence of strong preopercle spines (part of the gill covers) in the former. This feature also explains the family name Pomacanthidae from the Greek πομα, poma meaning "cover" and ακάνθα, akantha meaning "thorn". Many species of marine angelfishes have streamer-like extensions of the soft dorsal and anal fins. The fish have small mouths, relatively large pectoral fins, and rounded to lunate tail fins. The largest species, the gray angelfish, Pomacanthus arcuatus, may reach a length of 60 cm (24 in) at the other extreme, members of the genus Centropyge do not exceed 15 cm (5.9 in). A length of 20 to 30 cm (7.9 to 11.8 in) is typical for the rest of the family. The smaller species are popular amongst aquarists, whereas the largest species are occasionally sought as a food fish however, ciguatera poisoning has been reported as a result of eating marine angelfish. The queen angelfish grows to be 45 cm (18 in). With neon blue and yellow scales and iridescent purple and orange markings, surprisingly it is not conspicuous, and actually hides very well, and is very shy.