Indian Vagabond Butterflyfish

Chaetodon decussatus is a species of butterflyfish (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.

Description

Growing to a maximum of 20 cm (nearly 8 in) long. Their base colour is usually cream-white but can be beige to brown as well. They've a purplish-grey pattern of the typical diagonal stripes and the vertical black eye bar. The dorsal fin and last part of the body is black and the anal and caudal fin are yellow with a black stripe through it. All in all they look like a dark version of C. vagabundus.

Distribution

Indo-West Pacific: Maldives, India, Sri Lanka, Andaman Sea and the westernmost portion of the Indo-Malayan Archipelago.

Habitat

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.

It belongs to the large subgenus Rabdophorus which might warrant recognition as a distinct genus. In this group, it almost certainly is a rather close relative of the Threadfin Butterflyfish (C. auriga) and the Vagabond Butterflyfish (C. vagabundus). C. decussatus might be closer to the Threadfin Butterflyfish than to the common Vagabond Butterflyfish; as C. vagabundus has yielded abnormal DNA sequence data this is hard to say however. The C. auriga species group shares the characteristic pattern of two areas of ascending and descending oblique lines; species differ conspicuously in hindpart coloration.