These samples (N=42) were from two closely related mangrove killifish species with different mating systems (self-fertilizing and outcrossing) and including sympatric and allopatric conditions along the six coastal sites of south and south-east Brazil. We examined the skin microbiome composition to partition the influence of the genotype and the environment on their microbiome and epigenetic profiles. DNA was extracted from the collected swab samples and 16S rRNA-V4 region was amplified using the 515F-806R primers. Final library quantification was performed using qPCR prior to sequencing on a MiSeq Illumina platform. Finally, obtained sequence data were processed through quality checking and further downstream analysis.