when my tank has"matured" enough for a nem (which wont be for a whhile) i was wondrering if i would have to get rid of all my fish but the clown. i nhave a 12 gal Ap w/ 1 bicolor blenny 1 green chromis 1 ocellaris clown. if i get a nem would i bbe able to keep corals too? shrimp?