do u have a pump or is it ok to do a water change every couple of days??
I have my boys in 1 gallon - 3 gallon containers/tanks (different sizes) However in a pinch I have used a 2 liter soda bottle. (with the part where it starts to form into the opening of the bottle cut off of course) (Upgraded to a gallon the next day, and then a 2.5 gallon a few months later) So nearly anything in a pinch will work.
If you get a 1 gallon container (same with a 2 gallon, etc) - you don't nessarily have to filter it. Just keep up on your water changes. Personally I change my gallons once a week and my larger tanks and the 20 gallon every other week. My 20 gallon is filtered - the rest are not.
If you want you could add a bubbler to the water - just keep it on a very low setting....
To see exactly when the water should be changed, I'd suggest getting an ammonia test kit. Test the water once per day - when you start to see the ammonia, then you know it's time for a water change.
If I were you I'd definatly pick him up! (Then again I love rescuing fish)