I would never sell a fish to someone that I knew was sick. Also, when shipping a fish I make sure to pack it well.
I bought a fish from a seller with 100% feedback on Aquabid, did a side deal. He shipped it with NO insulation, only a double bag that was wrapped in newspaper. He killed that fish. It boiled. Will not respond to emails, won't give my money back, can't even leave feedback because it was a side deal. It was a gorgeous Peruvian flounder, over four inches
Man, did that box reek! I've got pictures if anyone wants to see how that fish arrived!
Sellers who sell sick fish or pack so poorly that the fish will surely die are terrible! I've only had a couple bad experiences buying over the net, and this was one of the worse!