guy bought some fish I ordered but he said he took them from a tank where some fish had rot or something as he wasn't sure but there was something. It wasn't white spots and most likely rot. So he said he will keep the fish for few days before selling to me to make sure they are fine.
Now, the question is that if fin rot is contagious like if one fish has all the water is contaminated or no? Specimen he picked are fine and have no rot or something.