Yellow tang in defensive position

My yellow tang has been acting odd lately. It is swimming around the tank ONLY in it's defensive position with it's spines pointing up. Does anyone know why it would be doing this? It is eating fine and looks healthy.

 

Dude, mine did the same thing for about a week or two. Have you added anything like corals, or re-arranged anything?? Mine was trying to establish that the new frag in the tank was his. It passed after awhile.

 

Well, I didn't add anything new recently put I did rearrange a little bit of rock a few days ago. maybe that's freaking him out?

 

possible

 

Yup, its either that or he's seeing himself in a reflection of some kind. My tang does the same thing when my kids place a mirror on the outside of the glass. Its funny to watch.


Luna

 

Alright I hope he's just freaked by the new rock scape. The only time that I've seen him not in the defensive position in the last couple days is when he's sleeping.