My perc was a nice vibrant orange and white when I bought him, and for a long time afterward. Lately, however, he has been developing a little black coloration on his belly, with a few little spots of it in the orange coloration. he seems to be doing fine, and it doesn't look like a disease really, more like a natural coloration. Any suggestions as to what this might be?

with an image i cant say for sure, but it sounds like its just getting more black color, this is not abnormal for true Percula clowns