Culture performance and tissue fatty acid compositions of yellow perch (Perca flavescens) fed different dietary lipids

The partial or total replacement of fish oil with soybean oil or flax oil in yellow perch Perca flavescens rearing performance and tissue fatty acid compositions were evaluated using five isonitrogenous (43.2%), isolipidic (8.5%), and isocaloric (21.3 MJ/kg) diets in a 15-week trial. Dietary treatments consisted of: 1) FO, containing 100% fish oil, which was used as a control; 2) FO:FXO, a 1:1 mixture of fish oil and flaxseed oil; 3) FXO, containing 100% flaxseed oil; 4) FXO:SO, a 1:1 mixture of flaxseed oil and soybean oil; and 5) SO, containing 100% soybean oil. Partial or complete replacement of fish oil with flaxseed oil (FO:FXO and FXO) resulted in similar final body weight, weight gain, specific growth rate, and feed efficiency compared to fish fed the FO diet, but fish fed the FXO:SO and SO diets had lower weight gain, specific growth rate and feed efficiency compared to other treatments. Somatic indices were similar for all diets except for gonadal somatic index which was higher for SO. Fillet proximate composition was similar for all diets; however replacing fish oil with different vegetable oils resulted in decreased n-3 fatty acids and increased n-6 fatty acids in various tissues. When fish oil was completely removed, concentrations of 20:5n-3, 22:5n-3 and 22:6n-3 decreased by 70, 46, and 33%, respectively, from values for fish fed the FO diet. Flaxseed oil can partially replace fish oil in the diet of yellow perch while maintaining growth performance and a favorable n‐3:n‐6 fillet fatty acid profile.

► Alternatives to fish oil can improve the sustainability of aquaculture.
► Five isonitrogenous, isolipidic, and isocaloric diets were used in a 15-week trial.
► Combinations of fish, flaxseed, and soybean oil were used for yellow perch.
► Flaxseed oil can effectively be used to replace fish oil in yellow perch diets.