Black Spot on CBB fin?

[asylumdown]

I've got an otherwise extremely healthy copper band butterfly in QT right now on his third transfer of the tank transfer method. He's fat, curious, active, and eats everything, so by CBB standards he's doing great. However, he has these weird black spots on his rear fin, and his left pectoral fin. They look like little pieces of charcoal dust have gotten stuck to him. They're not growing or changing, but I'm not sure if this is a parasite or infection of some sort.

I tried to take the best picture I could, but a) I have an iPhone, and b) he moves his pectoral fins too much to get the camera to focus on it, so I could only get a clear shot of his rear fin:



and from today:



They're all going to be getting a week of Prazi-pro after the tank transfer protocol is finished, but should I be looking in to something extra for him?