How to store fresh mussels: It's best to cook mussels the day that you buy them. To store for up to 2 days, transfer the mussels to a bowl or unsealed container and covered with a clean damp cloth or paper towel. Drain any water that collects in the bottom of the bowl every day. Do not store the mussels in water as they will die from it.

How to tell if mussels are fresh: Fresh mussels should be alive with their shells closed. They should have a fresh salty ocean smell, and not a fishy smell. If they smell fishy, I would not suggest eating them. If your mussels are store in the refrigerator, give it a smell just before cooking to ensure freshness.

How to store cooked mussels: You can store cooked mussels for up to 2 days in an airtight container in the refrigerator. To reheat, heat in a skillet over low heat until warmed through. You may have to add a little water if the sauce has thickened up too much in the refrigerator. I would not recommend freezing mussels.