Natural versus artificial seawater: Impacts on antioxidant capacity, muscle quality and gut microbiota of Acanthopagrus schlegelii during temporary rearing

For temporary blackhead seabream rearing, both natural seawater (NS) and artificial seawater (AS) are used at seafood markets for freshness. However, their effects on growth and muscle quality are unclear. This study explored the impacts of NS and AS on temporarily reared blackhead seabream. Various rearing periods (0, 3, 6, 9, 12 and 15 days) were tested, evaluating indicators like antioxidant capacity, morphology, muscle quality, and gut microbiota to uncover differences in rearing conditions. The results indicated that blackhead seabream reared in NS had a higher total antioxidant capacity. On the 9th day of temporary rearing, the Viscero-Somatic and Hepato-Somatic index of the NS group were lower than those from AS (P < 0.05). During rearing, the NS group showed significantly higher crude protein and lipid contents than the AS group (P < 0.05). Intestinal microbiota analysis revealed distinct compositions between the groups, with Proteobacteria dominating during rearing. Ralstonia was the dominant bacterial genus, higher in the NS group. Conversely, Ahrensia and Bacteroides were more prevalent in the AS group. In conclusion, this study revealed on impacts of temporary rearing without feeding on blackhead seabream in NS and AS. NS group exhibited enhanced antioxidant capacity and muscle quality, with increased beneficial bacteria in their gut microbiota.