I have 2 mystery snails Quarantining in a 10 gallon tank. I decided to do this after it seemed like they gave one of my fish black spot diseases. They are not doing so hot for some reason, they're both curled up in the corner out of their shells not moving. I'm pretty sure they're still alive, but I don't think they'll live much longer like this. I just cleaned their tank the other day and they looked a lot better but now they're doing the same thing... So I had them quarantined for several weeks and my fish still has the spots on her fins, so i don't know if i should just put them in the main tank or if that will make my fish worse if the parasites can transfer to the snails and back to the fish... Advice?