The Indian vagabond butterflyfish (Chaetodon decussatus), also known as the blackened butterflyfish or black-finned vagabond, is a species of marine ray-finned fish, a butterflyfish belonging to the family Chaetodontidae. It is found in the Indo-West Pacific, from the Maldives via India, Sri Lanka and the Andaman Sea to the westernmost portion of the Indonesian archipelago.
The Indian vagabond butterflyfish has a silvery-white body marked with diagonal grey lines and with a broad black vertical band running through the eyes. The posterior lower part of the body is largely black. There are yellow markings on the tail and anal fins. Growing to a maximum of 20 cm (nearly 8 in) long, it is found on rich coral reefs and also on rubble and rocky areas. The monogamous adults swim in pairs and may be territorial and aggressive to other Chaetodon; juveniles are solitary. The Indian vagabond butterflyfish feeds largely on algae and coral polyps. They are oviparous.[2