Help, not sure what this is. I have a yellow tail damsel that has a bug holding on to it's mouth. I don't know what it is, but looks like a potatoe bug. Those bugs that crawl on the ground outside and when you touch them they roll into a ball. The fish doesn't look bothered by this, but is swimming around normally. I tried to feed him, figured he'd open his mouth and bug gone, but doesn't appear to be able to open mouth. Also tried to catch him to see if I could remove the bug, but too fast.