Now I've got the survivors -- 7 rosy tetras and one bleeding heart -- in one quarantine tank, and I've picked up another 10 rosies which are in my other quarantine tank.
Assuming the disease was NTD or similar, what are the chances of the survivors being carriers now? Once they pass their four week quarantine, would it be safe to put them into the big tank, or should I put one or two quarantined rosies into their tank with them to make sure they don't get sick?
I'd hesitate to do that because I figure if anything's harbouring the disease it's more likely to be the filter, which I'll bleach before I hook it up to the big tank anyway. So if my survivors had the strongest immune systems, but I add a weak fish which gets sick from low levels of toxicity in the filter, I'm running the risk of creating a big reservoir of infection and getting my survivors sick again.