Poor thing. The only thing you can do for him is to keep the water as clean as possible--aquarium salt will help, and you may want to treat the water with a small amount of methylene blue to help prevent secondary infections. If you use methylene blue, you should do so in another container since it can be very harmful for invertebrates and plants.
I use rubbermaid/sterilite plastic storage bins from walmart/target. They are only about $3 each and are very durable and safe for fish. They can be safely heated, also.
They haven't been infected by any bacteria--there's no need to treat them for an infection if they don't have one. The medicine will just put more strain on their systems. Just keep the water super super clean--I would put them in separate containers because other fish will definitely pick on them if they're left with other fish.