Fishy tasting food

Dumela! That means hello in Setswana.
I just don't get it. We keep buying food that tastes like fish. I'm not talking about the fish tasting like fish. I'm talking about chicken that tastes like fish. The first time I thought it was a mistake. Maybe they had cut up the chicken on the same cutting board as the fish without washing it first. No more buying chicken from that store. Then we bought some chicken from a different store, and IT tasted like fish. The beef seems to be ok, so far, anyway (knock on wood). Last night we cooked some chicken that we bought already frozen (I think it was processed in South Africa). It tasted like chicken! I guess that's what we'll have to do from now on. Buy frozen chicken.
Last night we also opened a new 2L of milk. Guess what, it tasted like fish! I couldn't believe it! Is it too much to ask that ONLY the fish I buy tastes fishy?!