There is some black stuff that seemed to possibly have gotten in my tank from a yellow lab i bought 2 weeks ago, now it is currently on 4 fish and from what i can find online, it seems to be some sort of parasite...has anyone ever dealt with this b4? How would you handle this? i have another tank that they could be transferred into, but i dont want to infect the fish currently residing in the smaller tank...hmmmm, what are my options?