One bacterial strain was taxonomically characterized by means of a genomic approach comprising 16S rRNA gene sequence analysis, multilocus sequence analysis (MLSA), the DNA G+C content, whole genome analyses (ANI and GGDC), and phenotypic characterization. The strain CAIM 1540T was isolated from a cultured oyster Crassostrea corteziensis in La Cruz, Sinaloa state, México. The isolated was catalase and oxidase positive, cells were motile, O/129-sensitive and facultative anaerobic. The almost-complete 16S rRNA gene sequence placed this strain within the genus Vibrio; the closest species were V. aestivus, V. marisflavi, V. maritimus, and V. variabilis with similarity values of 99.02, 97.05, 96.70, and 96.59% respectively. MLSA of four housekeeping genes (ftsZ, gapA, recA, and topA) was done with the closest species. The DNA G+C content of this strain was 43.7 mol%. The ANI values with V. aestivus were 89.6 (ANIb), 90.6 (ANIm), and a GGDC value of 39.5 ± 2.5; with V. marisflavi the genomic similarities were 71.5 (ANIb), 85.5 (ANIm), and 20.2 ± 2.3 (GGDC); with V. maritimus 72.6 (ANIb), 85.7 (ANIm), and 22.0 ±2.0 (GGDC); and with V. variabilis 72.6 (ANIb), 85.8 (ANIm), and 21.6 ±1.6 (GGDC). The ANI and GGDC values are below the threshold for the delimitation of species, 95-96% and 70, respectively. Phenotypic characters also showed differences with the closest species analysed. The results presented here support the description of a novel species, for which the name Vibrio mexicanus sp. nov. is proposed, with strain CAIM 1540T (=CECT 8828T) as the type strain. In addition, we found that the recently described species V. thalassae and V. madracius might be a single species because the values of ANIb 95.8, ANIm 96.6, and GGDC 70.2 ±2.9 are above the species thresholds.