Fish slapping tails ?

[Z06-Hec]

so i have 2 questions...
My tangs occasionally turn and look like they are trying to slap each other with their tail... is this a way that tangs fight?
Purple and Powder blue


Another question
I just aw my 2 angels rubbing their tails together, no where near the slapping action the tangs do, but literally staying in place and rubbing their tails together..
Majestic Angel adult
Blue Face angel adult

 

[Triggreef]

Yes they have a razor back there by there tail. Seriously.

 

[eatbreakfast]

Yes they have a razor back there by there tail. Seriously.

Yp, another common name for tangs is sureon fish, because of the sharp bone that protrudes from the base of the caudal peduncle.

 

[Triggreef]

edit: surgeon

 

[Z06-Hec]

I've read that about Tangs... I cant possibly see them actually strike with enough accuracy to actually hit one another.... they just turn quickly like a tail whip...
Ok so anyone on my other question?

I caught my 2 angles rubbing their tails together... was cool to watch and very uncommon from them. The blueface is a hider, she is always in her rock and only comes out from time to time when she thinks no one is watching. They even started turning sideways while rubbing and continued to rub while turning. So from upright to sideways. This happened for a good 30 seconds which is pretty long for them to be still and accurate like that.