Lattice Butterfly

[pegrochilakila]

Hello everybody im new guy in this hobby, i just started 3 months ago.-
I get my fish from Wai's calgary, i get a clown, yello tail damsel and a lattice butterfly, the problem is that my butterfly is picking all the time on my mushroom corals, i have quite a few of them, this guy in the store told me that this lattice will be fine with my corals (soft corals) but i get to the point that i put it inside of a little quarantine tank cus it is going to finish wit my mush.-
Like a said im a complety new in this so im kinda desperate i need any help possible, what can i do with this fish ??
can i try buying special food for butterfly fish?
should return him to the store??
Any advice please.-
Thanks to all of you and God Bless you