Butterflies do not stay out of trouble in a reef.
However, I keep them anyway, so it is a tradeoff for me.
In my 230g, I have a red sea golden bfly, a blackback butterfly, and a pakistani butterfly. They eat zoo skirts and gsp like there is no tomorrow.
They keep the sps polyps retracted until they go to bed. So far there has only been one sps that they attacked in full eating mode.
I feed them a lot, and they all eat nori so I think that helps keep the munchies down a bit. They are fine with clams which was a bit of a surprise and bonus for me.
As always YMMV.
