Looking for tankmates advice

Help please. I've found over the years that I pretty much suck at maintaining a reef tank, but my fish are happy and growing. Since I can't successfully grow coral to fill my tank, I'd like to add a couple fish to make my tank more interesting.

I've currently got a brown tang and a yellow tang, a royal gramma, and a single chromi survivor from an initial group - i used to have clowns in the tank and they really bullied things until i took them out.

I do have mushrooms that are slowly taking over the tank, and i'd like to keep that going, so i don't think angels are an option.

Any good recommendations on fish that would fit in with what i have and be fun to watch? This is a 75 gal tank, btw.

 

Angels won't really eat mushrooms...but if ud rather not risk it you could get a wrasse they are a nice lively colorful addition