Some of the fattier fish like mackerel and herring can be a good source of Vitamin D and some fatty fish like sardines can provide a reasonable amount of Vitamin A, but most fish are not considered to be a particularly good source of fat-soluble vitamins. Some types of seafood can provide a good source for some minerals. Canned fish such as salmon and sardines that contain bones which are softened during the canning process can be a good source of calcium, but most fish flesh doesn't provide a significant amount of calcium. Seafood can also be a good source of phosphorus, and many processed and frozen products contain added phosphorus. Some types of shellfish such as clams and oysters are a good source of iron, zinc, magnesium, copper, iodine, and other trace minerals.
Most fish contain moderate to small amounts of most minerals.
Nutrient Composition Information Consumers frequently have questions about the amount of specific nutrients in various kinds of seafood. Because seafood is commonly sold from bulk displays in retail seafood markets and supermarkets, nutrition information that can usually be found on a package label isn't available. Many retailers provide nutrition charts that can be used to help consumers compare one type of fish or shellfish to another. In 1990 Congress passed the Nutrition Labeling and Education Act which required the U.S. Food and Drug Administration to examine and make changes in the nutritional labeling of foods. The FDA decided that retailers must voluntarily provide nutrition information on bulk foods like seafood and fruits and vegetables by displaying or giving customers access to nutrient information for the 20 most frequently consumed products in each category.