Tired of banging my head, help pick a fish

[mark]

Guess I'm probably focusing more on the negatives but seems every time I settle on a fish, I read or hear something like has a taste for clam mantles or love of cleaners. It's obvious I'm a little paranoid as there's lots of picture of people with beautiful reef tanks with angels and butterflies.

Realizing that each fish is unique but just how fearful should I be that, for example, a Long Nose Butterfly, a Flame Angel or Hawkfish is going to decimate my tank of of every invertebrate I can get my hands on.

Have a 145g with a Purple Tang and 2 clowns that never seem to go lower than 4 inches from the surface. Currently the only things are some polyps, mushrooms and xenia but I've gone through a bit of effort on this tank to have a reef but still would want some more fish (along with some SPS and LPS's, maybe a clam and love those shrimp).

Looking for something that can handle a 4-5" spoiled PT, would do more than float near the surface and lastly not go totally carnivore on me.