My Naso killed my Sargassum Trigger, err made him jump/carpet surf . I attribute that to tank size, only 125gal, then them both being identically sized and shaped. Currently the Naso and my Lei Trigger (considerably larger then the Sarg) are pretty close buds and swim alot of time side by side.
Agreed that Naso genus tangs are probably the most peaceful tangs out there, their catch of course is their size. White Cheek, as in Acanthurus nigricans, like all Powder tangs, is definitely up there as far as aggression. It's not a Sohal or Clown, but if he doesn't shine to someone, it will be brutually apparent. Though ultimately, I'd be a bit concerned with tank size and the Naso. If you get one in the 3"-4" range, you'll have probably around 2 years before he could use something bigger. My Naso was in my 125gal for a bit over that, and you could tell he was ready for something bigger.
If you are set on the Naso, I'd definitely move him up the addition order list. Other then that, I can't guess an exact timeframe for how long ocellaris clowns and the CT will work together, but I'm sure you aware of that.
