Okay, so it is more opportunistic. Her tail fin is a bit shredded, so I'm guessing the fungus got excited when she was in the dirty bag water and latched on. So frustrating. There are two spots on her tail fin. One spot looks like a white fuzzy dot and the other is a larger area that is white and looks fuzzy as well. It isn't round, but more of a patch. I'll start treating with Pima tonight. I hate this. I'll have to turn of my skimmer and filter - and I just added 4 fish! Grrrrrr!