Oxidative stress and growth performance are modulated by polyunsaturated fatty acids in Arctic charr, brook charr and their reciprocal hybrids.

In fish, polyunsaturated fatty acids (PUFAs) are essential structural elements in cellular membranes, participate in pathway regulation and act as important energy storage sources for optimum growth performance. However, they are also highly susceptible to peroxidation and thus potential oxidative damage. Omega-3 fatty acid content can vary among individuals and populations of fish and can therefore modulate their health status or resistance to oxidative stress. Our objective was to modulate [Formula: see text] omega-3 content in fish through different diets and estimate its impact on growth performance, overall fatty acid composition, oxidative stress parameters and antioxidant activity. We conducted experiments on juveniles (1) of four salmonid groups: Arctic charr ( brook charr () and their reciprocal hybrids. We found that growth performance in the four groups was negatively affected by high dietary fatty acid content. The content of thiobarbituric acid reactive substances (TBARS, a marker of lipids peroxidation) significantly rose in Arctic charr when fed the omega-3-rich diet. It was also observed that individuals with high docosahexaenoic acid and low [Formula: see text] omega-6 content had lower TBARS content. Consequently, high omega-3/omega-6 ratios were accompanied by lower oxidative stress levels. This supports the utilization of omega-3/omega-6 ratios as a marker of the ability of fish to modulate oxidative stress both in the wild and in an aquaculture context. This will further help to predict responses to environmental or nutritional modifications.