Nature Diary
Indian vagabond butterflyfish

The 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.
Growing to a maximum of 20 cm 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.
It almost certainly is a rather close relative of the Threadfin Butterflyfish and the Vagabond Butterflyfish. All share the characteristic pattern of two areas of ascending and descending oblique lines that make the fish so conspicuous and colourful (see cover photo).
It is the state animal of Lakshadweep, a group of islands off the Kerala coast forming the smallest Union Territory of India. They are grouped into the Amindivi group islands (consisting of Amini, Keltan, Chetlat, Kadamat, Bitra and Perumal Par) and the Laccadive group islands (comprising mainly Androth, Kalpeni, Kavaratti, Pitti and Suheli Par).
Together with Minicoy Island, Amindivi and Laccadive islands form the
Coral Islands of India in the Arabian Sea. All these islands have been built up by corals and have fringing coral reefs very close to their shores. Since the Indian Vagabond Butterflyfish feeds on alage and coral polyps, they are found in large numbers near these islands. They also use crevices in the coral reefs to hide themselves in at night time, even changing their colouration to blend in.
Coral islands
A coral island is formed by small organisms called polyps. Polyps are the builders of coral. These tiny organisms protect themselves by building small walls of limestone around their bodies. These creatures live in small colonies, and over millions of years, these 'settlements' become reefs, and then turn into islands.