I bought some of these Fish Antibiotics. They will be expired in 2018, but what I did learn from digging and research is that, Antibiotics are good for at least 5 years. There is a study from the US Army, that had a bunch of antibiotics and they were all expired and instead of throwing them out they had tested them for potency etc and just like that they were still very effective. There are some that you absolutely cannot use after expiration but only one or two. So do your research.