A yellow tang, or Kole yellow eye tang would be Okay (preferably the yellow eye, which can go in a smaller tank when its mature, whereas the yellow might need a bigger tank when mature due to its size or aggression), but an upgrade to 90g or 100g in the future would be more than enough room when he gets big. If you want an angel, get a dwarf, like a coral beauty or flame. both of those angelfish aren't known to be Coral unsafe but you are really taking a roll with some dice, if you plan on doing a reef, if not, almost all the dwarves would be fine in a 40g and some true angels would be okay in a 100g. Ive got a yellow tang and a coral beauty in a 55g and they've got plenty of room IMO, and my tang shows not one bit of aggression like i was told by LFS it would. My tang is like 5" now and when i add fish all it does is tag along with it and learn how it acts. Then it goes to work eating my hair algae
