I've used tiny barbless hooks (size #26 for ice fishing) on 2 1/2" Anthias. Never tried it on a angelfish - but it might work. You need to keep tension on the line as you haul them up, or they throw the hook. It's imperative that you tie the hook on well - if the line comes off, the hook will be left in the fish's mouth. I need a magnifying glass and two hemostats to tie the line on a #26 hook - these come with a magnet to keep them in one place when you work with them. Try baiting the hook with 1/2 of a frozen mysid. You usually get one, maybe two tries at this, then the fish gets wise...
Believe it or not, there is a group of people on R/C that suggest quickly turning on all the tank lights at 3am or so, and then poking around in the rocks and netting up the stunned fish as it bumps around the tank in shock. Seems more stressfull that even using a hook and line to me, but they didn't think so.....I guess I'll never know, because I won't be doing that here at the public aquarium I work at - can you imagine the carnage? I don't even allow our night security to use flash lights because it stresses the fish. Besides, I'm not all that interested in driving in to work at 3am (grin).
Jay