I tried the fish meds but they barely did anything. I ended up getting an extra bottle of pharmaceutical grade. The quality of the other antibiotics you can get are too poorly regulated. I'm not willing to bet my life on them. Yes they do last a long time but I'd like them to last as long as humanly possible. They may last 5-7 years or more, but they do deteriorate in quality (and therefore efficacy) after the first year or two. Probably not by much but it's just best practices. As a general rule I try not to expose things like that to temperature fluctuations, same as food or seeds or anything else. I'd rather do that for no reason, than need them, go to use them, and realize they're bunk.