I considered getting 1 for my 46. Soon to be moved into a bigger tank. So my lfs ordered one for me. When they came in they were HUGE. They have those long fins, they like to stretch them out. IMO I believe that these fish should be kept in a bigger tank then a 72. I have never kept one, but these fish were rather big. So when it says that they need room to swim, then you need to have ALOT of room. If you have a lot of rockwork it could become crammed when the buterfly gets bigger. I THINK that you could start with one in a 72, but it COULD out grow it. The ones that were at the lfs were rather large. I guess it would also depend on the dimensions of your tank. That is just my 2 cents. Like I said I have never kept one before.
