Sorry, but I would have to say that your tank is way too small for these guys. I have a mated pair and they are the most active swimmers in my tank, more so than even my tangs.
They are fast swimmers and make many quick 'jolts' across the tank, especially when the male is chasing/courting the female.
They are never just 'hanging out' in the rock work.
They are also a fairly large fish, most males comming in at 5" or larger with females almost, if not, as big. I've heard they can grow to 6+". At this size, they will be very cramped in your 65.
I had a friend try to keep a pair in a 75 gallon and they both wound up on the floor within days of purchase. Of course, this happened during the night and he found them both the next morning.
My humble opinion is that they should not be in any tank smaller than 6'. At 36", these fish will be banging off the sides all day long.
No offense intended.

Heres some pics of mine just for fun