PHOTO: SHARIF SARWAR

A juvenile semicircle angelfish glowing under the Bay of Bengal off Saint Martin’s Island. Native to the Indo-Pacific, from the Red Sea and East Africa to Japan and Australia, these angelfish drift through coral reefs, lagoons, and rubble slopes, sheltering in crevices when startled. Their diet is eclectic and reef-bound: sponges and tunicates form the core, with algae and small invertebrates rounding it out. With age, the inky blue fades into greenish-blue, a bold black mask forms, and the tail turns bright yellow. Listed as Least Concern by the IUCN, the species still faces local threats from coral loss due to rampant water pollution.