In this study, the feasibility of using pomegranate seed oil (PSO), rich in conjugated linolenic acid and its partial replacement for fish oil in fish diet were investigated. Common carp, Cyprinus carpio, juveniles (1.8 ± 0.1 g) were fed four isonitrogenous and isolipidic diets with similar basal composition but different oil mixture containing 100% fish oil (A), 50% fish oil +50% sunflower oil (B), 50% fish oil +25% sunflower oil +25% pomegranate seed oil (C) and 50% fish oil +50% pomegranate seed oil (D) for 8 weeks. The highest weight gain was observed in fish fed diet D (p < 0.05). Test diets had no significant effect (p > 0.05) on saturated and monounsaturated fatty acid contents of fish muscle. Docosahexaenoic acid (22:6n-3; DHA) was significantly lower in the muscle of fish fed diet B (p < 0.05) compared to those fed diet A. However, there was no significant difference in the muscle DHA content of fish fed diets A, C, or D. No specific hepatocyte damage associated to dietary pomegranate seed oil was found in this study.
Results of this study revealed that the partial substitution of fish oil with PSO (50%) in the Cyprinus carpio diet results in an improved growth performance. However, there was no significant difference between the body proximate composition and fatty acids profile (except for conjugated linoleic acids and n-3/n-6 ratio) as compared to the control group. Moreover, it also causes the transfer and accumulation of punicic acid in the muscle of fish and thus increases the nutritional value of fish. This study showed PSO can be introduced as a sustainable novel aquafeed ingredient for further supplementary studies, for example, expression of genes associated with peroxisome proliferator-responsive enzymes and liver health indexes plus additional prolonged experiments, which can shed light on the findings of this study and verify whether PSO is a practical novel aquafeed ingredient.