The fish and aquaculture activities produce an important volume of by-products due to discards and processing on board and in land. These residues (fillet cuts, bones, heads, viscera and tails) require to be processed in order to not create a significant environmental problem and to maintain the economical viability of the fisheries sector. The present paper reviews a list of recent patents on fish by-products applications, specifically on the products with the highest added value, such as fish protein hydrolysates and fish oil. Initially, an assessment is presented of the processes and techniques employed to obtain fish protein hydrolysates, which are classified by their utilization: ingredients for food, products for animal feeding, bioactive compounds, fertilizers, cosmetics and nutrient media for bacterial growth in specific industrial processes. Secondly, the different methods to extract the oil from the fish, to refine the fish oil avoiding undesirable taste and odour and to improve the stability of the mentioned oil, are evaluated. Finally, procedures for the microencapsulation of the oil obtained and its incorporation into food compositions have been surveyed.