Dietary prebiotics and synbiotics modulate gut microbiota and improve growth performance of Mexican pike silverside Chirostoma estor

Aquaculture is the fastest-growing food production sector worldwide and is vital for a sustainable animal protein supply. However, optimizing fish performance in captivity remains a major challenge, requiring functional diets that support a healthy holobiont. This study evaluated the effects of balanced experimental diets supplemented with inulin or yeast cell wall (prebiotics), Lactobacillus acidophilus (probiotic), or their combination (synbiotics) on juvenile pike silverside ( Chirostoma estor ). Growth performance was monitored, and gut microbiota composition was characterized by 16S rRNA gene metabarcoding. Synbiotic and yeast cell wall supplementation significantly improved growth parameters, including weight gain, final body weight, and specific growth rate, compared to the control. Microbiota profiling revealed a core community of nine genera ( Bacillus , Citrobacter , Cutibacterium , Lactobacillus , Pseudomonas , Spiroplasma , Stenotrophomonas , Streptococcus , and Thermogemmatispora ), with each treatment inducing distinct shifts in bacterial composition. Candidate probiotic taxa, including Lactobacillus spp., were also identified as part of the gut microbial response to dietary treatments. Functional predictions further indicated an enrichment of bacterial biosynthetic pathways in synbiotic and yeast cell wall treatments, aligning with the observed improvements in growth and feed efficiency. These findings indicated that yeast cell wall and synbiotic supplementation modulated gut microbial composition and were associated with improved growth performance in C .  estor , underscoring the role of microbiome-targeted nutrition in this species.