The term “sashimi-grade” is used by restaurants and fish sellers to describe the quality or freshness of fish. In reality, the term is nothing more than a marketing term that consumers associate with fish that they may safely eat raw.
Neither the Food and Drug Administration nor any government agencies or industry groups provide a standard definition or guidelines for labeling fish as sashimi-grade or sushi-grade. Supermarkets, fish stores and restaurants often use the term to describe fish they feel is of sufficient high quality or freshness to be safely consumed raw, or used to prepare sushi. However, nearly all fish contain harmful parasites and microorganisms and must be frozen at some point before it may be safely consumed raw.
For example, salmon frequently contains roundworm larvae that cause illness in humans if consumed. Most salmon catchers flash-freeze the fish on the boat immediately after catching. Food and Drug Administration guidelines specify the temperature and length of time necessary for killing parasites found in fish. However, cross contamination can occur during preparation even when preparers adhere to these guidelines.