LOL there is realy NO way of telling accept for seeing them in action..... there are some fish considered reef safe but there is still no telling. Coral beauties for instance are considered reef safe. I have one that picks at every single coral i have.... on the other hand i had a coral banded buttefly that didnt pick, also had a clown trigger that was fish, reef and invert friendly..... witch in most cases is hardly ever heard of.
Anyways make a long story short i can give you a few names of Fish Considered to be reef safe.
Almost all Clowns/anenomy fish.
Coral beauties are almost the only angle fish that is reef safe
Flame angles are for the most part reef safe but can be agressive to other fish.
Niger Trigger the only real reef safe trigger
Surgeons/Tangs Alot of tangs are reef safe, and probably the most beautiful fish IMO. Short list of popular reef tangs. Powder Blue, Powder Brown, Timiny, yellow, Purple, kole, unicorn, sailfin, scopas... etc. plenty of different tangs
Stay away from poisonous fish Scorpion fish, Lion fish. They can be beautiful but in general if something happens. Rock scape falls and they get smooshed or die, Their toxins can kill everything in your tank. Same goes for Poisonous inverts, witch there are alot of.
If you have a question about any fish you are interested in PM me. Or send a post on here there are tons of knowlegable people. Thanks =D