Assuming you will be going to the Coral Reef National Monument I would guess just any detailed Caribbean fish/coral guide would be fine.
As far as I know that is where the majority of the common hobby fish come from.
Anglers, Angels, Puffers, Triggers, Hogfish, Gobbies, Groupers, Sea turtles, Eels, Cuttlefish or Squid, Jacks, Blennies, Wrasses...and that's just off the top of my head.
Hope you have a great time!
and take lots of pics if you can!