Any member of two unrelated groups of fishes: freshwater species in the genus Brachydanio (family Cyprinidae) and saltwater species in the genus Pterois (family Scorpaenidae). The zebra danio (Brachydanio rerio), a popular freshwater aquarium fish originally from Asia, grows to about 1.5 in. (4 cm) long and has dark blue and silvery longitudinal stripes. The distinctive saltwater zebra fishes (Pterois), used in marine aquariums, have extremely large pectoral fins, numerous extremely poisonous spines, and colourful vertical stripes. Some species are more commonly known as lionfish and turkeyfish.