Im about to swap from a 75 to a 180. Once the tank is running for a month or ao, I will be adding a copperband butterfly and blonde naso. I wanted to order from Fish Hotel but Dierks doesn't do these two fish. Im looking at Dr Reef which I will definitely place their fish in an observation tank. The naso it looks like it can get in 2.5-3.75" which is about the size of my other tangs. The copperband comes in 1-3" or 3-5". My tangs and foxface are in 3-4" range. My tomini is the smallest at 2.5"+/-. Which size butterfly would you recommend?