Enoplosus armatus is a species of perciform fish, the only species in the family Enoplosidae.

It is native to reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

s in the Indian

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and western Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

s, and to the coastal waters of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

.

Originally classified with the butterflyfish

Butterflyfish

The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. Found mostly on the reefs of the Atlantic, Indian and Pacific Oceans, there are approximately 120 species in 10 genera...

es, it has a similar deep and compressed body but is easily distinguished by its silver-and-black zebra

Zebra

Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

-striped coloration, and by its two prominent dorsal fin

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

s, the second of which is very long, sickle-shaped, and has poisonous spines. It grows up to 50 cm long.

A fisherman's name, Old wife (plural: Old Wives), refers to the sound it makes when caught, caused by it grinding its teeth. The vernacular names include Bastard dory, derived from the french doré (golden), and Zebra-tail or -fish.

The first description of the species in 1790, one of the earliest of an Australian fish, was by John White

John White (surgeon)

John White was an English surgeon and botanical collector.White was born in Sussex and entered the Royal Navy on 26 June 1778 as third surgeon's mate. He was promoted surgeon in 1780, and was the principal surgeon during the voyage of the First Fleet to Australia...

 in Journal of a voyage to New South Wales. His description as Chætodon armatus (The Long-Spined Chaetodon) was as follows:

Chaetodon albescens, corpore, fasciis septem nigris, spinis pinnae dorsalis sex, tertia longissima.

Whitish Chaetodon, with seven black stripes on the body. Six spines on the dorsal fin, the third very long.

This appears to be a new and very elegant species of the genus Chaetodon. The total length of the specimen was not more than four inches. The colour a silvery white, darker, and of a bluish tinge on the back; the transverse fasciae, or bands, of a deep black; the fins and tail of a pale brown. The third ray or spine of the first dorsal fin is much longer than the rest.

This was accompanied by an illustration that is attributed to Thomas Watling

Thomas Watling

Thomas Watling was an early Australian painter and illustrator. Originally from Scotland, he was transported as a convict to Sydney, in the newly established Colony of New South Wales, in 1792 for forging banknotes. In Sydney he worked with John White, the colony's Surgeon General, copying...

, with a caption of The Pungent Chaetedon.