These formalin baths seem to be doing the trick to get rid of whatever fungus my clowns have. It's probably brook but I don't see any mucus or anything and they've had it for months. From what I hear brook moves QUICK but whatever it is it appears to be dying off after treatments with sulfur, pimafix (worked twice initally), melafix, and copper power! This stuff is doing it and maybe in a couple weeks they can finally hit the dt!