Short answer
Freezing is the standard way to reduce the risk of parasites in fish that will be eaten raw, and it is commonly recommended for salmon used in sushi or sashimi. But freezing is not a guarantee of safety. It does not remove bacteria, and many home freezers do not get as cold as the freezing methods in official guidance. Eating raw fish always carries some risk, and this article is general information, not medical advice.
Why freeze salmon before eating it raw
Wild salmon, and fish that spend time in the ocean, can carry parasites such as anisakid roundworms. Freshwater fish can carry others, including tapeworms. Cooking kills these parasites, but raw preparations skip that step. Freezing for a long enough time at a cold enough temperature kills them, which is why regulators and restaurants rely on it.
Do you have to freeze farmed salmon?
This is debated. Some sushi professionals note that farmed salmon raised on processed feed is rarely associated with parasites, and FDA guidance treats certain farmed fish raised in controlled conditions differently from wild-caught fish. However, you usually cannot confirm how the fish in a typical store was raised, handled or fed. If you are preparing salmon raw at home, the cautious approach is to freeze it, or to buy fish that the seller has specifically labeled and handled for raw consumption.
What does “sushi-grade” mean?
“Sushi-grade” and “sashimi-grade” are marketing terms. They are not a regulated safety standard in the United States. A label can mean the seller handled the fish with extra care, but it is best to ask the fishmonger directly whether the fish has been frozen to parasite-destruction guidelines and whether it is intended for raw use.
FDA freezing guidelines
The FDA’s guidance for fish intended to be eaten raw describes these options for parasite destruction:
- Freezing and storing at -4°F (-20°C) or below for 7 days total.
- Freezing at -31°F (-35°C) or below until solid and storing at that temperature for 15 hours.
- Freezing at -31°F (-35°C) or below until solid and storing at -4°F (-20°C) or below for 24 hours.
These are designed for commercial equipment and handling. For home cooks, the most relevant point is the first one: at least 7 days at -4°F or colder.
The home freezer problem
Food safety guidance for home freezers recommends 0°F (-18°C), which is warmer than -4°F. A household freezer may also fluctuate whenever the door opens. If you want to follow the 7-day guideline, you would need a freezer you have verified, with a thermometer, holds -4°F (-20°C) or lower. Many home freezers, especially the compartment in a refrigerator, may not. If you cannot confirm the temperature, treat home freezing as a partial safeguard rather than a guarantee, or choose fish that was commercially frozen for raw use.
How to freeze salmon step by step
- Start with very fresh fish from a source you trust, kept cold the whole way home.
- Portion it into pieces you will use in one go, so you do not have to thaw more than you need.
- Pat it dry with clean paper towels.
- Wrap tightly in plastic wrap or, better, vacuum seal to remove air.
- Add an outer layer such as a heavy-duty freezer bag.
- Label with the date and freeze at the coldest setting, ideally in the coldest part of the freezer and away from the door.
- Keep it frozen for at least the time and temperature in the guidance above before using it raw.
Some cooks also dry-cure fillets briefly with salt and sugar and rinse them before wrapping. That affects texture and flavor but is not a substitute for proper freezing.
Thawing safely
- Thaw in the refrigerator, usually overnight, on a plate or tray to catch drips.
- Do not thaw on the counter or in warm water.
- Keep the fish cold and use it soon after thawing. Many sources suggest within about a day.
- Do not refreeze thawed raw fish.
- Use clean knives, boards and hands.
What freezing does not do
Freezing does not kill all bacteria; it mostly pauses their growth. Raw fish can still carry bacteria that cause illness if it is handled poorly or kept warm. Fresh handling, clean tools and cold storage remain important even when the fish has been frozen for parasites.
Who should avoid raw fish
Health authorities generally advise that pregnant people, young children, older adults and anyone with a weakened immune system avoid raw fish. If that applies to you or the people you are serving, cook the salmon thoroughly instead. The USDA recommends cooking fish to an internal temperature of 145°F (63°C).
FAQ
Should you freeze salmon before making sushi? It is commonly recommended, especially for wild salmon or fish of unknown origin.
Is it safe to use frozen salmon for sushi? It can reduce parasite risk when frozen properly, but it does not eliminate all risks, such as bacteria.
How long does salmon need to be frozen to be sushi-grade? There is no legal definition of sushi-grade. FDA guidance for parasite destruction includes 7 days at -4°F (-20°C) or colder.
Can you freeze salmon and eat it raw? Some people do, but home freezers may not reach the recommended temperature. Consider the limits above before deciding.
How long can salmon stay in the freezer before quality drops? Well-wrapped salmon can keep its quality for months. Vacuum sealing helps, and fish that has been frozen for a very long time may show dryness or off flavors.