Generally, fish, according to the Messinian Diet pyramid, are to be consumed 2 to 3 times on a weekly basis. In particular, fish, like red meat and poultry, constitute a key source of protein and are high in B vitamins and iron. Regarding their content of fat, it should be mentioned that this varies from species to species. There are low-fat fish, such as cod and sole and high-fat fish such as trout, salmon and mackerel. The fat of fish has been classified as ‘good’ fat and has been found to have overall positive effects on human health. Fish that contain less fat and seafood, like crabs and octopus, are an important source of omega-3 fats. Apart from fat and proteins, fish also provide the body with a number of vitamins and trace elements, such as the fat-soluble vitamins A, D and the water-soluble B complex vitamins (B1, B2, B3, and B12). Finally, the main minerals and trace elements that fish and seafood contain are calcium (especially small fish consumed with bones), phosphorus, zinc and iodine. Specifically, fish flesh has a high content of protein (at a rate of 18 to 25%), beneficial fat (mainly polyunsaturated omega-3), vitamins (fat-soluble A, D, E, K, B complex vitamins) and a significant amount of minerals (calcium, sodium, potassium, phosphorus, copper, iron, magnesium and iodine).