Thank you for your question.
Can sushi keep for a long period of time?
"As a general rule of thumb, the answer is no. Sushi is best eaten
fresh, insuring that you enjoy the full flavor of the ingredients -
especially the fish. It's recommended by local sushi chefs that sushi
be consumed immediately, or within two to four hours. However, if you
do decide to try and save your sushi, adhere to some of the following
guidelines: The first step would be to separate the rice from the
fish. Next, since sushi rice is mixed with vinegar, it doesn't pose a
problem storing it in a cool place. Just make sure that it's wrapped
securely. As for the fish, it is absolutely necessary that it go into
the refrigerator; otherwise, it will spoil! Again, be sure to wrap the
fish tightly. Although the sushi will be edible the next day, it
probably will have lost a lot of its flavor."
How long can I keep sushi in the refrigerator or freezer?
"Storage of Fresh Sushi/Sashimi Grade Seafood: Fresh sushi quality
seafood can be kept in the refrigerator for two days. It must be
covered with a bag of ice and kept in the coldest part of the
refrigerator. It can last up to a week in a freezer if tightly sealed
in a plastic bag or saran wrap. If you do not plan on eating it all in
two days, the best thing to do would be to eat as much as you can the
first night, then properly freeze the rest. To defrost it properly,
you should let it thaw in the fridge for 12 to 24 hours."
"Remember that cold goes down, so the coldest place in your
refrigerator is probably the bottom shelf."