Comprehensive insight into gut microbiota and their interaction with fatty acid profiles in Channa striata during the spawning season

Striped murrel (Channa striata) is renowned for its nutritional benefits, such as antimicrobial, antioxidant, anti-obesity, and anti-inflammatory properties, attributed to its rich content of short-chain and polyunsaturated fatty acids (SCFAs and PUFAs). Unlike many food fish, it successfully breeds in captivity, adding to its value. Despite its nutritional significance, specific composition of its gut microbiota and its influence on fatty acid (FA) profiles remain underexplored. This study investigated sex-specific differences in gut bacterial communities and their association with FA profiles across two rearing conditions: fish maintained in water tanks (T1) and those reared in pond-simulated habitats (T2). Gut tissue samples underwent high-throughput 16S rRNA gene amplicon sequencing (V3-V4 region) and muscle tissue samples were analyzed for FA profiling. Significant variations were observed across habitat and sex. Habitat influenced FA and microbiota composition, with females from T2 showed higher palmitic (44.32%) and linoleic acids (12.01%), while T1 females had greater oleic acid (32.32%). Pseudoalteromonadaceae (Pseudoalteromonas) and Salmonella enterica were enriched in T1 than in T2. Females exhibited distinct FA profiles dominated by palmitic, oleic, and linoleic acids and sequencing results showed greater species richness and shannon diversity in their gut microbiota, with a higher abundance of Alphaproteobacteria. Males, by contrast, had higher levels of Clostridia and Fusobacteriia. Functional predictions revealed that females exhibited higher enrichment in energy metabolism, lipid biosynthesis, and xenobiotic biodegradation, while males showed greater enrichment in nucleotide and amino acid metabolism. Key microbial taxa such as Methylobacterium organophilum, Pseudomonas stutzeri and Faecalibacterium prausnitzii contributed to PUFA synthesis and antioxidant production. Co-occurrence networks in female displayed stronger interactions and connectivity compared to male. Notably, Cetobacterium somerae, Clostridium perfringens, and M. organophilum were key taxa in females, while Propionibacterium acnes, M. organophilum, and Plesiomonas shigelloides were prominent in males. Overall, the findings highlight sex- and habitat-specific gut microbiome dynamics that shape the FA composition of C. striata, offering insights for aquaculture improvement and nutritional optimization.