Basic Guidelines For English Spellings
READ THESE ARTICLES
Any of various fishes with brilliant colours or markings, including the cuckoo wrasse, Labrus mixtus, and the peacock bass, Cichla ocellaris; (also) any of various fishes with conspicuous fan-shaped fins or tails, including the guppy, Poecilia reticulata, and tropical fishes of the genus Pterois (family Scorpaenidae).
Mid 17th century; earliest use found in Robert Lovell (?1630–1690), naturalist. From peacock + fish.