i have a small yellow tang in my 75.Hes doing ok.But am setting up a 180.If u can go bigger do it now.it will save u money.Everything I have read on here about tangs,says go bigger,atleast a125 long.they need long tanks to swim.My tang doesnt go up and down very much.He miss alot of food because of this.all the other fish get it all.they r up and downers.thats what i see and read.