zebra fish, any member of either of two unrelated groups of fishes, the freshwater species in the genus Danio (family Cyprinidae; order Cypriniformes) and the saltwater species in the genus Pterois (family Scorpaenidae; order Scorpaeniformes). The zebra danio (Danio rerio), a popular freshwater aquarium fish originally from Asia, is small (up to about 4 cm [1.5 inches] 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 by the names lionfish and turkeyfish.