Comparative Assessment of Synthetic and Algal‐Derived Astaxanthin Supplementation on Growth Traits, Lipid Homeostasis, and Liver Well‐Being in High‐Fat Diet‐Fed <i>Trachinotus ovatus</i>

While aquaculture often relies on excessive lipid intake to bolster fish growth and cut feed expenses, this practice can also result in hepatic fat accumulation, inflammatory responses, oxidative damage, and immune system malfunctions in aquatic creatures. Astaxanthin (AST), a potent antioxidant, holds promise in mitigating these detrimental effects associated with high-lipid (HL) diets. The objective of this study was to investigate the functional contributions and the fundamental molecular pathways of both synthetically produced and algae-derived Ast, focusing on their impacts on growth rates, lipid regulation, and hepatic well-being in juvenile <i>Trachinotus ovatus</i> maintained on diets rich in lipids. The experimental setup involved feeding <i>T. ovatus</i> for 8 weeks with four different diets: a control feed (CF) with normal lipid content, a HL diet, a HL diet supplemented with synthetic AST (HL + S), and a HL diet supplemented with algal-derived AST (HL + A). When compared to the HL diet, the inclusion of Ast from both sources in the feed significantly improved the growth performance and survival rate (SR) of <i>T. ovatus</i>. Furthermore, both forms of Ast significantly increased glutathione reductase (GR)activity and high-density lipoprotein (HDL) levels, while also decreasing the levels of lipid transport-related substances in the serum. They were also successful in mitigating hepatic lipid overload. Regarding antioxidant potential, the addition of Ast notably potentiated the Nrf2/Keap-1 signaling cascades and boosted the functionality of antioxidant enzymes. Furthermore, Ast from both synthetic and algae origins augmented the innate immune defenses of <i>T. ovatus</i>, leading to a decreased sensitivity to stress in the fish. To conclude, incorporating Ast from either source into the high-fat diet of <i>T. ovatus</i> mitigated the detrimental consequences of such a diet, including impeded growth, weakened antioxidant defenses, and weakened innate immune responses. Moreover, both sources of Ast exhibited beneficial effects on sustaining lipid metabolism homeostasis and enhancing hepatic well-being in the fish.