yeah, I would like to know because I had my betta and dwarf frog in with the rasboras until they got a columnaris infection (which I STILL cannot get rid of) and I took the two of them out and put them in a two gallon cooking cambro. I don't want to keep them in that (thank heavens they don't need a filter/heater/air pump). I was thinking about putting the betta in the 55, and the frog back in either the columnaris infected tank, or the ich infested tank, but certainly not if he's gonna catch it! ( I would put him in the 55, but it doesn't have a close fitting cover and he could escape...) So, surely there must be SOMEONE out there who knows the answer...
btw, I was thinking mostly of putting him back in the columnaris tank, I think the Ich medicine might bother him and I don't know how he'd do with gouramis...but the columnaris medicine is fine...