Mandarin Fighting Reflection

So i bought a mandarin a couple of days ago. he is wild caught. And I saw him attacking his reflection at the top of the water and on the side of the glass. I have no clue what is going on. And when he does it he goes out ito his full display

 

It will do that for a while then accept the other fish is not invading it's territory.

 

i had a yellow tang that would always do this right after i cleaned the glass, he would do it so much his tail would turn red with irritation.

 

My scooter Blenny does it sometimes too, They just dont like the idea of another male or same sex in the tank, and they cant tell the difference, Hell give it up eventually.