Batfish

These were known locally (Maldives) as Batfish but elsewhere called spadefish.
Although this looks like a night dive, it was just dark-ish and with a little tinkering in photoshop looked much better with a true black background.
This was during the diving live-aboard J&myself had in The Maldives. We had a school of these circling us for quite some time, so loads of time to hang there and try for the best shot I could.