Glassy Sweeper

Found in schools, during the day, sheltering in caves, crevices, under ledges, around harbours, and shipwrecks, foraging for food at night, high above the bottom, over shallow coral and rocky reefs.
They feed nocturnally on zooplankton.

Sweepers school during the day, but at night they float high above the bottom to hunt for larger zooplankton.
Several species are triangular shaped.