Okay I managed to find a small container that could hold 2 liters. Makes salt baths so much easier :)
I also found a aquarium store that can order in that Gel-Tek Ampicillin, so I'll be getting it just in case.
On a side note, Ryuk (the name of my friend's fish) is doing a lot better already. Although his physical appearance hasn't improved, his behavior seems to be a bit happier. :) He's swimming around a lot (which is an improvement from his very lethargic behavior when I first got him) and he even made a small bubble nest today!