Sushi Grade Fish

Fresh water fish, and fish that spend part of their lives in fresh water, such as Salmon, can have tapeworms. Some salt water fish can be infected with Anisakis, a very thin worm. All these are killed by cooking to 145°F/63°C, but may still be alive in raw fish that have not been properly freeze treated.

While only a few salt water fish are likely to have these parasites, why does the FDA require all (except Tuna) get the freezing treatment? About 30% of fish sold in North America are mislabeled at some point in the distribution system. Unless you buy whole fish, and know your fish well, you may not be getting what you are paying for, and that includes in fancy sushi bars. It should be noted that farmed fish are far less likely to have parasites because they are fed on pellets, not the natural foods from which the parasites originate. Tuna is excepted because it's not likely anyone would mistake some other fish for Tuna.

Both the tapeworms and Anisakis can infect humans. Actual infections are very rare, and usually non-fatal, but can be very painful. For details on these and other risks from fish and why mercury in fish is a non-problem, see our Health & Nutrition article.

These are the FDA requirements. Japanese requirements are similar.

• -4 °F/-20°C or below for at least 7 days.
• Flash freezing at -31°F/-35°C until solid and held at that temperature for at least 15 hours.
• Flash freezing at -31°F/-35°C until solid and holding at -4 °F/-20°C for at least 24 hours.

Actually, it is not easy for most people in North America to buy fish that does not meet these requirements. Most commercial catches are flash frozen at sea and held deeply frozen until landed. Farmed fish is usually flash frozen immediately or immediately after processing. This is required to preserve texture as slow freezing causes large ice crystals in the flesh, and not freezing immediately degrades the catch.

On the other hand, locally caught fish "just off the boat" may not be as safe. Some locally caught is flash frozen immediately by wholesalers for shipment to stores, but some may be sold to local vendors and restaurants without the necessary freezing protocol. Such fish is expected to be cooked, and thus made safe.

My freezer compartment just meets the FDA 7 day requirement, but most probably do not. In any case, it is sub-optimal to freeze fish that slowly. I buy my fish from the Asian markets here in Los Angeles. Usually I buy whole fish, so I know what I'm getting, It's usually been frozen solid since catch, and easily meets FDA requirements. Even so, I'd tend to use safe fish if eating raw.

For reference, here is a partial list of common sushi fish and their risk. Disclaimer: This table is based on knowledge of sushi chefs and fish biologists. It can not be considered absolute as there may be exceptions in nature, so caution is appropriate.

*1*   Large Barracuda living in tropical reef environments can carry Ciguatera Poisoning which can be very serious. See our Ciguatera Poisoning entry. Large Amberjack, Red Snapper, Grouper, and other predatory fish can carry this toxin. Pacific Barracuda sold in California is free of this problem. Barracuda, or any other of the Mackerel family, if not handled correctly, can also result in Histamine Poisoning.

*2*   Escolar is not a fish prone to parasites, and it is outstandingly delicious - but - even eating a normal serving can produce a severe case of oil leakage that you won't even feel, but you will certainly see the bright orange stains where you last sat. For details, see our Escolar page.

*3*   Tapeworm is the parasite most common in Fresh Water Fish. The big exception is Tilapia, because it is always farmed except in the rivers of Africa.