Blue Reef Chromis

Sep 13, 2017. Seen in Oil Slick Leap, Bonaire.
Body purple or bright blue, paler below, with black stripe. Black margin on spinous dorsal fin, upper and lower lobes of caudal fin and front of anal fin; no black spot at pectoral base. Adults are common above deep outer reefs and feeds in aggregations of the small zooplankton, primarily copepods .
http://www.fishbase.org/summary/Chromis-cyanea.html