Fish and fishery products, like many other animal products, contain water, proteins and other nitrogenous compounds, lipids, carbohydrates, minerals and vitamins. Proteins and lipids are the major components of fish. The essential micro-nutrients and minerals in fish, which are deficient in staples, include vitamins B, and in fatty fish, A and D, phosphorus, iron, calcium, magnesium, selenium and, in marine fish, iodine.
Fish lipids include up to 40 percent of long-chain fatty acids that are highly unsaturated, thus having positive health implications, but present a technical challenge in dealing with the rapid development of rancidity. Fish proteins, comprising of structural, sarcoplasmic and connective tissue proteins, contain all the essential amino acids and are an excellent source of lysine, methionine and cysteine. Several important chemical and biological take place in dead fish which, if appropriate measures are not taken, lead to spoilage. Globally, an estimated 10-12 million tonnes of fish are lost annually because of spoilage. In some developing countries, fish accounts for a high proportion of animal protein intake of the population. The high nutritious value of fish is particularly important for many lower-income groups who might otherwise depend on a cereal-based diet to meet their nutritional needs. Cereal grains are usually low in lysine and sulphur-containing amino acids so that supplementing the diet with fish significantly raises the biological value of the diet.
Projections of demand resulting from population and income growth point to an increasing gap between supply and demand. This is likely to impact particularly severely on levels of consumption by vulnerable groups.