At just two inches in length this appears to be the larval stage of a flounder. This image was captured a mile off the island of Yap at night with the bottom 1000+ feet below, Yap, Federated States of Micronesia

horizontal animal color colour glow close up night sea transparent underwater deep nighttime tourism tropical fish glowing larva larval vertebrate fishes tropical climate side view black background copy space full length animals blackwater larvae marine life black pacific ocean pacific nobody travel ocean one animal color image vertebrates water sea life close up travel destinations animals in the wild colour image no one no people flatfish yap micronesia flounder flounders larval stage facing right closeup reproducer reproducers