Why

I got home lastnight from working out of town and my blue tang decided to snap off a piece of sps. I got it about a month ago and it recently turned a bright teal/royal blue. It was my favorite piece. The frag plug is still encrusted but it was a frag about an 1" long. This fish is a pain in the a$$. It moves anything that is not glued down and snaps pieces it doesn't like.