I'm still holding off on treating my new PetSmart sale GBR pair for camallanus worms. 1 had clear, stringy waste, and also had a slight bout with ick after being in tank for 24 hours. Ick-Ease took care of that, and didn't even kill my shrimp. I'm holding off because treatment is no fun, and USPS suuuuccckkks.
The PetSmart I frequent is the best as far as lack of illnesses, cleanliness and selection, but you can't ever be too sure. Camallanus once, ok, but two times now in 5 months, @%!&. Quarantine, quarantine, quarantine. I'm feeling much dumber now, for not. Your mileage may vary
They won't accept fish, cause they can't properly quarantine them, but they'll sure as hell sell you...anything.