while i am a big fan of pushing the envelope, i would have quarantined the fish for 30 days or so first, if possible. remember that pet shops, no matter if they are a chain or independent use a central filtration system. what that means is that if the goldfish tank has a parasite, then you can be pretty sure that all the fish that are on that filter also have that parasite (where applicable). now, some do use multiple filtration units, but none use a separate filter for each tank. wouldn't be cost efficient. and just an fyi, guppies are NOTORIOUS for having parasites. i am good friends with several guppy breeders. now here is where i slightly disagree with Grif. not ALL parasites are transferable. the frog must be able to provide the same conditions as the fish does for it to survive. since they have different biological make ups, i would say you got a 50/50 chance whether or not a particular parasite could be transferred and make the pyxie it's new home. safer to quarantine, then dump the fish in, after a nice long acclimation.

you are running some sort of chemical filtration in the fluval, right?