Effects of replacing fish oil with shrimp waste, canola, and camelina oils on growth and fillet lipid quality in juvenile rainbow trout fed low-fishmeal diets

This study assessed the replacement of fish oil (FO) with camelina oil, canola oil, and Argentinian marine shrimp oil (from industry waste) in juvenile rainbow trout ( Oncorhynchus mykiss ) diets. Fish (initial weight 7.97 ± 0.83 g) were distributed into eighteen 100-liter tanks (36 fish per tank; initial density ∼2.9 kg/m³) and fed six experimental diets for 60 days at 3 % body weight per day. The diets were isonitrogenous (52 % crude protein) and isolipidic (21–22 % lipids). The experimental diets were FO (100 % fish oil), SH (100 % shrimp oil), SHCA (75 % canola + 25 % shrimp oil), COCA (75 % canola + 25 % camelina oil), CO (100 % camelina oil), and CA (100 % canola oil). Growth performance showed comparable outcomes across treatments. Whole-body proximal composition revealed stable dry matter content (96.05 % FO to 97.56 % SHCA) and protein content (50.25 % CO to 52.92 % FO). Lipid content was higher in SHCA (37.36 %) and COCA (37.28 %) diets, while FO (35.03 %) and SH (34.63 %) diets had lower levels. Protein was most digestible in FO (92.6 ± 0.56 %) and SHCA (92.5 ± 0.58 %) diets. Phosphorus digestibility was highest in SH-fed fish (69.7 ± 2.24 %). Fatty acid profiles showed higher saturated fatty acids (SFA) in FO and SH (33.43 and 27.36 mg g⁻¹, respectively) and long-chain omega-3s (EPA and DHA) in FO. CO and CA diets were rich in monounsaturated fatty acids (MUFA), with CA having 57.59 mg g⁻¹ . Fillet nutritional quality indices showed that FO (0.602 ± 0.005) and SH (0.586 ± 0.105) had the highest atherogenicity index and more favorable omega-6/omega-3 ratios (SH: 0.230 ± 0.023, FO: 0.267 ± 0.023).