The glassfish or sweepers in the photo like shady places during the day: wrecks, overhangs and caves. At night they venture out to feed on zooplankton.
Sweepers have large eyes and a single fin on their backs.. They are 10 cm long with yellow heads, peach-coloured bodies and a distinct lateral line running from head to forked-tail.
The Underwater Photographer: Digital and Traditional Techniques, by by Martin Edge, Paperback, 536 pages (2009)
Shipwrecks from the Egyptian Red Sea by Ned Middleton; Immel Publishing, 196 pages.