Since the first epidemiological studies, carried out in the '80s, established the protective effect of fish oil against cardiovascular diseases, the interest for fish oil and omega-3 fatty acids has been highly increased as well as the demand of omega-3 enriched products and nutraceuticals. As consequence, the searching of new omega-3 natural sources, the design of competitive fish oil and omega-3 production processes and the development of different strategies for omega-3 incorporation in food products have become important fields of research all over the world. In the last years, the valorisation of fish by-products as a source of omega-3 rich oil has been considered an outstanding strategy to reduce the waste generation and increase the competitiveness in the fish industry. On the other hand, the development of green technologies based on the use of supercritical carbon dioxide has acquired an enormous interest to produce high value compounds such as omega-3 in a eco-friendly way. This book presents an application of supercritical fluids in extraction, concentration and formulation of omega-3 rich oil using fish by-products as a raw material.