Triggers (and angels) tend to be bad tankmates for anglers. They pick at the sessile fish, and sort of pester them to death (and open them up for infections).
If you're getting a red emperor snapper (or worse, already have one), I hope you have a tank in the 500+gallon range. You know they get to almost 3 feet long, right? They also eat anything that can fit in their mouths, and the colors tend to fade as they get older.
Dave