Fish is good for us: this belief is one important reason for the growing consumption of seafood in the developed world. There is indeed good evidence that fish oils can contribute significantly to our long-term health. On the other hand, of all our foods, fish and shellfish are the source of the broadest range of immediate health hazards, from bacteria and viruses to parasites, pollutants, and strange toxins. Cooks and consumers should be aware of these hazards, and of how to minimize them. The simplest rule is to buy from knowledgeable seafood specialists whose stock turns over quickly, and to cook fish and shellfish promptly and thoroughly. Raw and lightly cooked preparations are delicious but carry the risk of several kinds of food-borne disease. They are best indulged in at established restaurants that have access to the best fish and the expertise to prepare it.