Recirculating aquaculture-fasting strategy (RAS-F) to modulate gut microbiota and enhance the fish meat quality of bighead carp (Aristichthys nobilis)

Intensive aquaculture often leads to a decline in fish quality, and requires a strategy to restore the post-culture quality of fish. This study presents a novel recirculating aquaculture-fasting strategy (RAS-F) and assesses its impact on meat quality and gut microbiota of bighead carp. Results revealed RAS-F notably reduced body lipid and protein, achieving weight loss and body reshaping. RAS-F decreased the hardness, increased the springiness, and effectively improved the texture. Off-flavor compounds, especially aldehydes and ketones, were diminished, while umami amino acids (UAA) increased significantly. Noticeably, fatty acid profiles shifted, with reduced saturated fatty acids (SFA) and significantly increased polyunsaturated fatty acid (PUFA). Gut microbiota diversity and richness improved over fasting, with key microorganisms (Cetobacterium, Bacteroides, Akkermansia) contributing to PUFA and UAA synthesis as well as the off-flavor compounds degradation. These findings highlight the potential of RAS-F to enhance fish quality and reveal microbial mechanisms, offering insights for post-culture improvement.