I went on vacation for a few days and left my fish with a neigbor, and when I got back, one of my females had velvet. We figured out where she got it from so we knew she had had it for at least 24 hours, and we started treating the tank.
Now, the other
female in the same tank (thank you for helpful remarks about how I should be keeping more than 2 together, they're fine) is showing NO signs of velvet. She has been bumping into the other one for days (not like scratching against her though) but she has no gold dust and she is eating and swimming around.
I thought maybe we had caught the parasite before it got to her, but the sick one still has it, so it's clearly still around. Is there some sort of velvet-immunity mutation that she could have? Or does she have parasites inside her that I can't see? I doubt that's even possibly for the parasites, since they get energy from photosynthesis.
What's going on?????