Is it safe to eat raw fish at home?

What the freezing requirement actually is, why "sushi grade" means nothing, which species carry which risk, and the handling that matters more than any label.

Difficulty: intermediate
Time: 10 min
Read: 5 min
Safety: warning

Short answer

Fish for raw eating must have been frozen hard enough for long enough to kill parasites — the legal standard is essentially -20°C for at least 24 hours throughout, or -35°C for about 15 hours. Buy fish that has been frozen for this purpose, or freeze it yourself only if your freezer genuinely reaches -20°C. Farmed salmon raised on pellet feed is exempted from the requirement in law; wild fish is not.

The two hazards in raw fish are completely different. Parasites — anisakis worms in particular — are killed reliably by freezing and not by chilling. Bacteria are not killed by freezing at all and are controlled only by how cold and how fresh the fish was kept. That is why a label saying "sushi grade" tells you nothing useful: it addresses neither problem, and no law defines it.

Safety

There is no such thing as legally defined "sushi grade" or "sashimi grade" fish in the UK — the terms are marketing and mean whatever the seller wants. The actual legal control is that fishery products intended to be eaten raw or lightly cured must be frozen to kill parasites, at temperatures and durations set in retained EU food hygiene law. Anyone pregnant, immunocompromised, very young or elderly should not eat raw fish. Bivalve shellfish are a separate and higher risk and are covered in their own guide.

Step by step

Understand what the freezing rule is for.It is a parasite control, nothing else. Anisakis larvae are present in a good proportion of wild marine fish, mostly in the gut and sometimes in the flesh. Freezing to the required depth and duration kills them; refrigeration does not, curing does not reliably, and neither does lemon juice.
Know the actual temperatures and times.Retained EU hygiene law requires fishery products to be eaten raw or almost raw to be frozen throughout to -20°C for not less than 24 hours, or -35°C for not less than 15 hours. Businesses must comply; at home you are relying on your own freezer meeting it.
Check whether your freezer can actually do it.A domestic four-star freezer is specified to reach -18°C, which is not -20°C, and a full freezer opened regularly may sit warmer than its setting. A cheap freezer thermometer settles the question. If it will not hold -20°C, buy fish that has been commercially frozen instead.
Treat "sushi grade" as a claim to interrogate, not a certification.Ask the seller directly: has this been frozen to the parasite-kill standard, and when? A good fishmonger will know and answer. A pack that only says sushi grade and nothing about freezing has told you nothing.
Know which fish are lower risk.Farmed Atlantic salmon fed on formulated pellets is specifically exempted from the freezing requirement in law, because the parasite life cycle is broken by the feed. Tuna caught and handled for the raw market has historically low anisakis prevalence. Wild cod, herring, mackerel and wild salmon are among the higher-prevalence species and should always be frozen first.
Take the bacterial half seriously, because freezing does nothing for it.Buy the freshest fish available, keep it on ice or in the coldest part of the fridge, prepare it cold, use a clean board and knife used for nothing else, and eat it the same day. Scombroid poisoning from histamine in temperature-abused tuna and mackerel is the most common fish-related illness in the UK and is entirely a chilling failure.
Cure and marinate as flavour, not as safety.Gravlax, ceviche and any citrus or salt cure change texture and flavour and reduce some surface bacteria. They do not reliably kill parasites. Cured raw fish is subject to the same freezing requirement as fish eaten completely raw.
Exclude the vulnerable groups.Pregnancy, immunosuppression, chemotherapy, liver disease, very young children and frail older people are all reasons to cook fish through. This is not over-caution; those groups take a much worse outcome from the same exposure.

Tips

Frozen-at-sea tuna and salmon loins are usually the most sensible raw-eating purchase available to a home cook, because the freezing was done properly and immediately, and they are cheaper than the counter.
Freeze fish for raw eating flat and in thin portions. A thick loin takes far longer for its centre to reach -20°C than the surface does, and the rule applies throughout the piece.
Anisakis is visible if you look — a fine coiled worm a centimetre or two long. Candling a fillet over a bright light will find some but by no means all of them, so it is not a substitute for freezing.
If you eat raw fish and get severe stomach pain and nausea within hours, mention raw fish specifically to a doctor. Anisakis infection is uncommon in the UK and is easily missed if you do not raise it.
Freshwater fish should not be eaten raw at all in a domestic setting — the parasite picture is different and worse.

Common mistakes

Buying "sashimi grade" and assuming it has been frozen — The term has no legal meaning in the UK. Some sellers use it to mean exactly the right thing and others use it to mean "our best fish". If you did not ask about freezing, you do not know.
Freezing fish in a domestic freezer and assuming that is enough — Most domestic freezers run around -18°C at best, and a busy one runs warmer. The legal standard is -20°C throughout for a full day. Close is not the same, and a thermometer costs a few pounds.
Relying on lime juice in ceviche to make fish safe — Acid denatures the surface protein so it looks cooked, and it does very little to parasites in the flesh. Ceviche made from fish that was never frozen carries the full parasite risk.

Questions people ask

Can I use supermarket salmon for sushi?

Farmed Atlantic salmon is the one common case where the law does not require prior freezing, because farmed salmon on formulated feed does not acquire the parasite. The bacterial side still applies fully: buy it as fresh as possible, keep it very cold, use clean equipment and eat it the day you buy it. If you want to be more careful still, freeze it yourself at -20°C for 24 hours first.

Does smoked salmon count as raw?

Cold-smoked salmon is raw — it is cured and smoked below cooking temperature. Commercial cold-smoked salmon is produced under controls that include the freezing requirement where it applies, which is why it is generally safe. Home cold smoking is a different matter entirely and carries real risk; there is a separate guide on it.

What about raw shellfish?

Different problem. Oysters and other raw bivalves carry norovirus and vibrio risks that have nothing to do with parasites and nothing to do with freezing. They are covered separately and the honest answer there is less reassuring than it is for fish.