Agreed that something is picking on him, whether you see it happening or not. The Trigger is easily #1 on the suspect list, but Flames can be aggressive too.
I've been following the other post with the Tomini with white patches and see other somewhat recent posts saying there was a blonde Naso, Dogface puffer, cardinals along with the Koran, Niger trigger and Flame Angel and only see that its a 55 tall tank...then a post about getting a 180 in early January. Did you ever get that 180g? Whats the status of that? What happened to the Cardinals, Naso and Dogface? Are they still around?
If these fish are in a 55tall, then a lot of the problems could be revolving around having them in too small a tank and really pushing the stocking. Get them into the 180g and I bet some of the problems disappear.
The Trigger is aggressive and in a tank 1/3 the size it needs. Its probably feeling the whole tank is it's territory. Talk to people that have had triggers and you'll see that is a recipe for disaster. The Koran is in a tank 200 gallons too small. It's gonna be stressed, even without aggressive tank-mates. Stress causes problems and fish in small tanks are stressed. Add semi and aggressive fish to the mix and the potential for problems increases.
