The moorish idol has a laterally compressed, disc-shaped body with a color pattern featuring alternating black, white and yellow bands of varying widths. Its long, threadlike dorsal fin extends gracefully, enhancing its elegance as it swims. Its caudal fin is black with a thin white edge, adding a touch of contrast.

The moorish idol is distinguished by its long, slender snout, marked by a distinctive yellow-orange saddle-shaped patch.

The moorish idol is widely distributed across the tropical and subtropical waters of the Indian and Pacific Oceans. In the Indian Ocean, it is commonly found along the eastern coast of Africa, from the shores of Mozambique and Madagascar to the Red Sea, as well as around the reefs surrounding islands like Réunion, Seychelles, Maldives, Chagos and other islands in the western Indian Ocean basin.

In the Pacific Ocean, the moorish idol is found in the western region, ranging from the Philippines, Papua New Guinea and Australia’s Great Barrier Reef to the islands of Southeast Asia. In the central region, it is seen around the Marshall, Hawaii and Kiribati islands, and in the eastern region, it ranges from the coasts of California to the Galápagos islands.

The moorish idol inhabits warm, shallow tropical waters and prefers coral reefs, lagoons and reef slopes at depths of up to about 150 meters, although it is most commonly observed at depths below 20 meters.

The moorish idol is generally a solitary species but occasionally forms small groups of several individuals, though it rarely swims in schools.

One of the main characters in Disney Pixar's animated film Finding Nemo, named Gill, the leader of the dentist office aquarium gang, is depicted as a moorish idol.

Due to their similar morphological features and coloration, the moorish idol is often mistaken for two other species of bannerfish that closely resemble it but are primarily found in schools: the common bannerfish and the schooling bannerfish.

Its widespread geographic distribution and striking appearance make the moorish idol an iconic tropical fish species of coral reefs worldwide.