Deveiopment in research and production of trout feed during the last years led to a remarkable reductlon of the environmental impact by improving the diet composition. important steps vvere the minimizing of the phosphorus content, the use of extruded feed instead of pelleted feed and tire increase of the energy (îipid) Ievel. Lipid-enriched higb-digestible diets with low phosphorus level are vvell utJlized, enable rapid growth of trout and contribute to decrease of aquaculture vvaste by diminishing the excreîion of phosphorus, nitrogen and organic matter. Nevv considerations are related to stabilizing the trout faeces by adding guar gum to the feed. İn future substitution of fisb meal with vegetable meals wi!l support the conservation of marine fısh populations. Enrichment of trout feeds with Osh oii results in marketable fisb with substantia! conceotrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These n-3 poJyunsalurated fatty acids are favourable for human health and have a beneficial effect especîally in preventing cardiovascular diseases,