I consider the LN butterfly to be an extremely hardy fish...mine was the first fish introduced after my initial cycle, went through multiple hypo treatments, tank moves, and living with tangs. he never skipped a beat and always readly fed.
i feed mine flake (form 1), fresh seafood (squid, octo, mussel, shrimp) and nori.
he's full grown at about 6-7" and resides in my 110gal FOWLR with my hippo and boxfish. he's always out in the open and takes no crap from the tang. he simply turnsd upside down and flares his dorsal spikes when the hippo trys anything and that stops the hippo in his tracks.
if you're looking for a butterfly than the LN is my butterfly of choice.
Brian