yeah I'm sure a little aggression is something that I'll always have to deal with. It seems like she's calmed down today, there are times where the angel and butterfly look like best buds and swim right next to each other, and other times where she's had enough of the butterfly.
She's definitely more aggressive just after feeding, and she will usually go after the butterfly if he's chasing his reflection. I think she mistakes his aggression towards his reflection, and thinks he's going after her.
Either way it's a little better today
hopefully she'll calm down further
Edit: just noticed the butterfly now has an opaque section on his tail, probably from the nipping :/