It was a surprise for me because I didn’t know that fish can be dangerous for a breast-fed infant. The main reason of it is mercury. Make sure you avoid shark, pike, albacore and halibut. Also, you should avoid dishes with marlin and swordfish. The worst effect that your baby can get from your milk, if you eat these fish, is development delays. It doesn’t mean that you should forget about fish food at all, just try to eat something like salmon or shrimps.