How long do mussels and clams last in the fridge?

The short version: live mussels and clams keep for about one to two days in the fridge, and ideally you cook them the same day or the day after you buy them. That window is short for a reason most fridge guidance does not have to deal with — the mussel or clam in the bag is, right up until you cook it, a living animal, and the entire point of storing it correctly is keeping it that way. Once it dies before it is cooked, the question stops being "how fresh is this" and becomes "do not eat this".

Why live shellfish are not just another seafood

Fish and shrimp are dead the moment you buy them, and everything about storing them is slowing down decay that has already started. Mussels and clams are usually sold alive, filtering water through themselves right up until they go in the pot. That is a different job for your fridge to do. It is not preserving a piece of tissue — it is keeping a small, cold-water animal alive and reasonably comfortable for a day or two, which is a narrower, less forgiving target than simply keeping something cold.

This is also why the usual smell-and-look checks that work for fish or chicken only tell you half the story here. A mussel can smell perfectly clean and still be a problem, if it is dead and you do not know it yet. The check that matters most for shellfish is not about decay at all. It is about whether the animal is still alive.

How to store them so they stay alive

Keep them cold, but do not seal them in and do not drown them. A bowl loosely covered with a damp cloth or paper towel, or left in the mesh or perforated bag they were sold in, lets them breathe while staying humid. An airtight container or a knotted plastic bag does the opposite of what you want — it traps them without oxygen, and they suffocate faster than the cold alone would spoil them.

Do not store them submerged in fresh tap water, even though it seems like the natural way to keep a sea creature hydrated. Mussels and clams are saltwater animals, and fresh water is lethal to them within a few hours — you would be killing the thing you are trying to keep alive. If a recipe calls for purging them in water before cooking, that is a short, deliberate step done close to cooking time with salted water, not a storage method.

Put them toward the back of a middle shelf, the coldest part of the fridge that is not the freezer, and away from the door. As with most seafood, a few degrees makes a real difference to how much time you actually have.

The tap test: checking before you cook, not after

Before cooking, go through them one at a time. A shell that is already closed is a good sign. A shell that is slightly open but closes on its own when you tap it, or give it a light squeeze, is also fine — that reflex is the animal responding, which means it is alive. A shell that stays gaping open after a tap, and does not close, is a shell with nothing responding inside it. That one gets discarded, not cooked.

Cracked, broken or unusually heavy shells are worth discarding too without debating it — a heavy one is often full of mud or sand rather than a live animal, and a cracked shell has already let in whatever was in the water or the ice around it. None of this takes long once you know what you are looking for, and it is the one step in this whole process that genuinely cannot be skipped.

After cooking: the shells that never opened

Cooking mussels and clams causes the muscle holding the shell shut to relax, which is why a healthy one pops open in the pot. A shell that stays firmly closed after everything around it has opened did not go through that process, and the standard, conservative guidance is to discard it rather than pry it apart to check. It is a small number of shells out of a full pot, and it is not worth treating as a puzzle to solve with a knife.

Buying, and why "today" is not always day one

As with a lot of seafood, the day you buy mussels or clams is not necessarily the day they were harvested — there is usually some time between the water and the shop, even for a product sold live. That is a reason to treat the one-to-two-day window as starting close to the purchase date rather than stretching it, not a reason to distrust the counter. Buying them the same day you plan to cook, or the day before at the latest, keeps the gap small enough that it stops mattering.

Once cooked, the meat behaves like any other cooked seafood — good for about three to four days refrigerated, following the same conservative window that applies to cooked fish and shrimp, not the tighter one to two days that applied while they were still alive.

What actually makes this easy

• Store loose and damp, never sealed or submerged. A bowl with a damp cloth over it beats an airtight container every time.
• Check before you cook, not after. A shell that will not close when tapped is telling you something you cannot get from a smell test.
• Buy close to cooking day. One to two days is the realistic window from purchase, not from when you finally get around to it.
• After cooking, let the pot decide. Shells that opened are fine. Shells that did not, are not — discard them without trying to force the question.

The part that trips people up is rarely the cooking itself — it is remembering which day the bag actually came home, once it has been sitting at the back of the fridge next to everything else bought that week. Munch logs the day something like this came into the house and puts it at the front of what needs using, so the one-to-two-day window is something the whole household can see, not something only the person who did the shopping is trying to remember.