Regal Tangs Bashing Into Finger Coral

[peesa]

I've noticed some odd behaviour from our two new juvi regal tangs. They seem to be bashing into/sort of hitting their sides against our finger coral?

Does anyone know why they may be doing this??

 

[SkiFletch]

Do they only do it to the finger coral, or do they do it to the rocks and other things too? Sometimes flicking and rubbing against objects is a sign of parasite infections. Sometimes its just a sign of a rash.