The amount of fish oil required for fish feed production is increasing, and already today about 50% of the world's total oil production is used in fish feed. The aquaculture industry is expected to have an annual growth of more than 10% in the coming year s. Fish oil will then certainly become a limiting factor for the feed industry. At present the supply of fish oil is rather volatile, and this has promoted a change towards a general inclusion of low levels of vegetable oils in salmon diets. However, it i s important to further access the effects of alternative lipid sources on fish health and animal welfare in general to learn more both about basic mechanisms involved and any requirement limits that may exist. The present project will study the effect of dietary fatty acids on: a) incidence of coronary heart disease in salmon, b) non-specific immune defence system, c) gene regulation of key madiators of inflammatory factors. The project will be coordinated with an EU-project termed Researching Alternatives to Fish Oil in Aquaculture, (RAFOA) which performs trials with diets containing different oil sources in terms of fish materials, briding of scientific disciplines and creating synergies.