120 gallon custom Tank build New tank mate ideas!!!

[Achilles]

So I've been thinking about adding a few new fish in my 120 gallon custom rimless tanks 72x24x20. Currently I have a White tail Brussels tooth Tang, scopes Tang, yellow assessor, about five chromosomes, algae blenny, vlimagie tang. So I am looking for a reef safe fish that is very friendly tank mates that serve a purpose in the reef. please if you have any ideas Post below!!!

 

[Daniel@R2R]

I like diamond gobies for sand stirring. Any particular functions you're looking for?