Yeah. I felt so awful. I bought 3 beautiful new guppies from our local (very much trusted) pet shop, and they were carrying some sort of flesh-eating thing that took out my whole lot of livebearers, including the special strain that I developed.
They were carrying it even after I quarantined them.
They seemed fine, and then my females stopped eating, became thin, shakey and were basically eaten alive by this thing. Skin, fins and all. I literally tried everything: salt dips, melafix, fungal and bacterial meds, etc, and I eventually had to euthanize them. They were obviously in misery.
I think that ended my guppy breeding for the time being.