The nutritional value of fish varies and it is associated with their chemical composition including the content of fatty acids. Differences are attributed, first of all, to the species of fish, but they depend on other individual features (size and sexual maturity, reproduction cycle) and environmental factors (fish nutrition system, season, water temperature and its salinity, geographical location of water body). The composition of lipids depends on the type of fish tissue the lipids origin from (muscles, roe, and organs). Fish oils obtained from different sources provide significant quantities of polyunsaturated fatty acids (PUFAs) with pro-health properties, although those quantities vary. First thing, the consumption of fish and fish oils helps reduce the risk of coronary heart disease and this effect is linked with the content of monounsaturated (MUFA) and polyunsaturated fatty acids in them. Another pro-health aspect of consuming n-3 PUFA acids results from their vital role in preventing and treating cardiovascular diseases, inflammations, aggression, depression, hypertension, autoimmune disorders, diabetes, renal impairments, rheumatoid arthritis, underdevelopment of brain and eyes in infants, allergy, and neoplasms. Muscles and liver are those main organs where the lipids are stored in the body of fish. Raw roe and caviar are luxury products; however, they are characterized by a high nutritional value as they contain MUFA and PUFA. A high level of DHA and EPA along with an advantageous n-3/n-6 ratio in fish are major factors in the balanced eicosanoids synthesis in human body. In different regions and countries, the above named products are still perceived as a traditional food of local importance.