> Blue Butterfly (might be Angel?)

It's a Blue Tang, a Surgeonfish.

> One stripe yellow fish

It's a Yellowtail Snapper.  There's also a Sargent Major in the photo.  The fish at the bottom of the same picture may be a Jack of some kind or another Yellowtail.  It's hard to tell without being able to see the colors better.

> Many striped yellow fish etc.......

That's most likely a juvenile grunt of some kind, but I can't be sure.  I don't have my identification books here and there are several fish that look similar when they are young

I'm giving a Slideshow talk to the Photographic Club and there's
sure to be a smart a**e in the audience who will correct me :-(
Thanks for any help.

Tell him/her that your talk is about photography, not fish identification.

Lee