Darting

My Yellow Tang is behaving unusual. He is usually swims around king of calmly but today he is doing a lot of short darting movements.
I added my cuc last night, could this cause anything.

 

I think it is quite normal behavior. The 2 I had both did it. It is like they are either agitated (snout gets a little Red) or they are full of ---- and vinegar (feeling their oats).

 

The same thing happened to my purple tang when I add a fish or coral or cuc member. But goes away. I think it might be aggression towards the new addition ... Specially if you've had this fish for a sum period of time and params are in check.

 

I looks like an aggressive action.
I also put my MH on today, ever since hes been in the tank hes only had RO florescents on him.. maybe he's hyped up

 

Same here...mine does that every once and a while too. I got worried at first as well, but like others said I think its just some wacky normal behavior.

 

Strange. He as some thin long string coming from his anus, its a brown color. Looks like a thick hair about 2" long. He's darting all over the place trying to scape his bottom now.
Breathing heavy, I don't know if its because of his extra energy he's using or what!
My clown has a white one the same hanging out of his. What is going on here?