How many days would you leave a bag of mussels in your fridge?

Glad to have this topic revived. Kary Osmund's fishmonger is right that mussels can keep for more than a day or two, but it takes some work as well as acceptance that you're going to lose some. A lot of people start getting pretty nervous when mortality rates go up towards 10%.

Oysters keep much, much better than mussels, and a week is more reasonable. There are many who'd argue with the screwdriver advice, but I've found that oyster-opening preferences are extremely personal. I have one friend who insists on using my clam knife--which is sort of like going the opposite direction of the screwdriver.

And pea crabs. They are not dangerous in mussels or oysters. When I was in grad school, we had a mussel-harvesting area that always had pea crabs, and we (well, some of us) grew to love that little crunch!

I recently purchased oysters from a reputable fishmonger and he advised me that oysters can keep for a week in the fridge! I only kept them overnight. They were still alive when I wrestled them open (interestingly, he said using a screwdriver is better than an oyster knife, less injuries for the oyster opener) and there was still a live crab parasite looking thing on the inside of some oysters as well. We tossed those oysters that had the crab things.

I spoke with my fish monger from the St. Lawrence Market in Toronto and this is what he said, "the truth is that they will last over one week with less than ten percent loss, but people find the idea uncomfortable. I'd only add to your instructions a daily drain and replenishment of ice on top of the towel to both hydrate and cool.". So, mussels will keep if they are properly stored in the fridge for up to one week. Just make sure you're storing them in the fridge, in a colander, over a lipped plate, and covered with a damp towel or newspaper (that you're changing everyday). Here's more about how to pick, store and prepare mussels: http://karyosmond.com/how-to-cook-live-mussels/

I just remembered another mussel-buying point. While it's my preference to know and love my fishmonger, some people don't have access to a great one. My brother, would lives inland, buys his mussels at Costco. They come in bags identifying their source and the date that they were pulled from the water. I've had them and they're really fresh.

While I basically agree with you ChefJune, I think your advice is most important for mussels. Oysters are a completely different story. They have much thicker shells and the advantage of one side being more rounded than the other. Packed round side down, they survive pretty well. Even in the 1800s, growers on the East Coast packed them up and shipped them inland. Knowing that, I wouldn't mind keeping oysters on ice for a couple days if I lived somewhere that I couldn't get them on the day I wanted to eat them.

I don't buy them if I am not going to serve them the same day. I am like that about any mollusk or shellfish in its shell. The animal needs to be alive when you cook it.

Use them as quickly as possible -- preferably the same day you buy them!

I agree with everyone. Mussels are more fragile than oysters and hardshell clams. If you are somewhere where you can buy them on the day you are eating them, that's what to do. If that's impossible, putting them on top of--not in--ice is okay. But regardless, toss any that won't close or have cracked shells.

I always use them the same day, as I am touchy about seafood. Industry says "a few days" if stored correctly. See http://www.discovermussels.com/storing

I think the question is - are they still alive? They usually open a bit when you leave them alone - tap them - if they close back up they are alive and OK, if they don't they are dead and you need to chuck them

Overnight at most. Make sure they are resting on ice. Some people have said you can hold them longer but I'm not one of them. You don't know how long they've been out of the water when you buy them. Mussels are a safe, sustainable seafood (if you don't let them spoil).

I keep them in the fridge no longer than the day after I purchase them. Preferably, I buy them the same day I am going to cook them. But if you are buying from a reputable fishmonger, they should be able to advise you.