I have 2 clowns and 2 balas in QT right now, had them for almost 2 weeks. I just noticed a tiny black line on the tail of one of the clowns, about the lenght of a pencil tip, maybe half that width. I looked up anchor worms, but those look white. Any idea what else this might be? I also just saw one of the clowns flash for the first time, but no signs of ich. I will obviously be keeping them in QT for quite a bit longer, but not sure what to treat for if anything otherwise, fish seem very healthy and happy