I must apologize for the dark photo. I was trying out a Kenko 1.4 TC on a 60mm and only had one strobe on the camera for the day. I was unable to light the fish very well as a result. These fish were inside a limestone cave about 30 feet. At first I did not notice they were upside down until after I had taken some photos. They were remaining motionless along the base of the walls and would swim away as I approached, all upside down. What are they?
I would go with Cardinal fish of some sort ... I can't help you anymore .. but armed with that info a search on fishbase.org might help you as you know your area you were diving in.
It is the Bluestripe Dwarfgoby (Trimma tevegae). You can find more info about it here: