Fish Oil Replacement by Camelina (Camelina sativa L.) Oil in Diets for Juvenile Tench (Tinca tinca L.): Effects on Survival, Growth, and Whole-Body Fatty Acid Profile

SIMPLE SUMMARY: The total replacement of fish oil (FO) with camelina oil (CO) in the diets of juvenile tench (Tinca tinca L.) did not have negative effects on survival rates or growth performance. When juveniles were fed with diets containing levels of CO of 40% or higher, lipid content in whole-body tench was significantly lower than those fed the control diet whereas linolenic acid content was significantly higher. No differences in total saturated, monounsaturated, or polyunsaturated fatty acids were found in whole-body juveniles. The nutritional indices were within optimal values for healthy foods for human consumption. ABSTRACT: Tench (Tinca tinca L.) plays a key role in the diversification of inland aquaculture, but its culture is mainly based on extensive culture systems with usually low and unpredictable yields. Rearing procedures under controlled conditions are essential to promote and consolidate tench production, and it is necessary to set up adequate feeding in early growth phases. Fish oil (FO) is currently the main source of lipids in aquafeeds, but considering the stagnation of smaller pelagic fisheries, alternative oils should be addressed. In a ninety-day experiment, the effects of partial and total replacement of FO with camelina oil (CO) on juvenile tench growth performance and whole-body composition were evaluated. Six isonitrogenous and isolipidic diets with different levels of CO were tested: 0% (control), 20%, 40%, 60%, 80%, and 100%. The survival rate was 100%, and no significant differences in growth performance (total length, weight, specific growth rate, feed conversion ratio, and biomass gain) were found. The lipid content in whole-body juveniles was significantly lower when juveniles were fed diets containing 40% and higher levels of CO than those fed the control diet whereas linolenic acid content was significantly higher. No differences in ΣSFA, ΣMUFA, ΣPUFA, Σn − 3, or Σn − 6 whole-body content were found. The nutritional indices ΣPUFA/ΣSFA and Σn − 6/Σn − 3 showed a linear increase trend with dietary CO inclusion whereas the EPA + DHA showed an opposite tendency. Compared to the control diet, EPA + DHA content (g kg(−1)) was significantly lower in juvenile tench fed a 100% CO diet, and Σn − 6/Σn − 3 was significantly higher in juvenile tench fed 80% and 100% CO diets. Overall, the results indicate that the total replacement of FO with CO in diets is feasible without negative effects on growth performance whereas the nutritional quality of juvenile tench was unaffected with a maximum replacement of 80%.