Copperband Butterflyfish strange behavior

[Terri Caton]

My fish is big, fat and happy. But, about every 2 or 3 months it gets weird for a few days. It acts like it’s scared and hides. Fins flared. Still eats but only if the food comes to where it is hiding. Usually it’s a pretty aggressive eater. After a couple of days it starts to come out of hiding. By day 4 or 5 it’s behaving normally. No mate. No other fish bothering it. No changes to the tank.

Any theories?

 

[Biff0rz]

Mine has done the same, I didn't think it was normal either.