I am in the process of upgrading from a 75 to a 125 gallon mostly sps reef tank. I have had a longnosed butterfly for about two years (whom by the way has been a model citizen as far as not disturbing corals or clams). I am contemplating the purchase of a Red Sea Sailfin or a Purple tang for the 125. Any comments regarding compatability of tangs and butterflies would be appreciated. While I would hate to see him go, I would be willing to part with the Butterfly in order to accommodate the tang. Also, would a 6 ft. long 125 tank be large enough for a red sea sailfin? the RC staf in their thread recommend 130 or larger. He would be the only tang.