These samples belong to reference (REF) and gilthead sea bream genetically selected for growth (GS) were fed with CTRL (15% FM, 5-7% FO) or FUTURE (7.5% FM, 10% poultry meal, 2.5% DHA-algae oil) diets over a 12-months production cycle. Samples from initial (t0 Nov-19), intermediate (t1 Jul-20) and final (t2 Nov-20) sampling points were used for Illumina 16S rRNA gene amplicon sequencing of the adherent microbiota of anterior intestine (AI). Samples from the same individuals (t1) were also used for the gene expression profiling of AI by RNA-seq, and subsequent correlation analyses with microbiota abundances.