Pretty sure that is part of his gills, not something someone stuck around him. Seems to me that if you put something around a fish he would thrash around to get it off.
I'm still not entirely sure what to make of it. The scales on the fish's head look bubbled... those "things" coming out from where his gills should be look like peeled/boiled off scales... but the rest of the fish seems to look ok. :\