I have a powder brown tang that has been a model citizen. No problems with aggression or munching until this week. He has decided he likes my leather polyps. Both leathers are complaining!!! I'm hoping that when the new tank is set up (probably in a couple of months) that things will improve as the leathers will go into the new tank. Hopefully he won't develop a taste for something else.
In the meantime, the leathers might have to be moved to the refuge with very low lighting.
I agree a proper diet will probably go a long way to avoiding ich. I have a veggie clip in my tank to hold daily portions of sushihane, dulse (both types of nori - seaweed for human consumption) as well as tang heaven, ulva or grape caulpera. When the clip is empty, I add more.
Vickie