The main ingredients of fish feed have traditionally been of marine origin but these ingredients are becoming both scarce and expensive. The fish farming industry therefore wishes to utilise alternative lipid (fat) sources in feed used for salmon farming. Vegetable oils also tend to increase growth rate and carcase quality of fish. However, when fed to patients, notable differences were found. The fat composition of the salmon meat affected the fatty acid profile of the patients’ blood and the advantageous marine omega-3 fatty acids increased markedly in those patients that ate fish fed on feed containing pure fish oils.