Ok, I am turning to my fellow fish keepers for some wisdom here... About a week or two ago I noticed a green growth on one of my angelfish's pelvic fins. It looks like algae and I thought maybe he rubbed it off a plant, but the thing never came off. I have never heard of algea growing on a fish... is it possible? or is this something else? If it is harmful how should I remove it? I greatly appreciate any comments/advice.

