A Gram-negative, aerobic, short rod-shaped and non-motile bacterium, designated SWA25(T), was isolated from Chinese fermented fish sauce in Shantou, Guangdong Province, China. Strain SWA25(T) was moderately halophilic, formed colourless colonies and grew at 10-45 °C (optimum, 37 °C) and pH 4-9 (optimum, 6-7) in the presence of 0.5-22.5 % (w/v) NaCl (optimum, 3 %). The major cellular fatty acids (>10 %) were identified as C18:1 ω7C, C16:0, C16:1 ω7c, and C19:0 cyclo ω8c, and the predominant respiratory ubiquinone was Q-9. The genomic DNA G+C content was 61.3 ± 2.1 mol %. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SWA25(T) belonged to the genus Halomonas in the family Halomonadaceae. The closest relatives were Halomonas xianhensis A-1(T) (96.5 % 16S rRNA gene sequence similarity), H. lutea DSM 23508(T) (96.5 %) and H. muralis LMG 20969(T) (96.1 %). DNA-DNA hybridization assays showed 30.7 ± 2.6 % relatedness between strain SWA25(T) and H. xianhensis A-1(T), and 39.4 ± 4.1 % between strain SWA25(T) and H. lutea DSM 23508(T). On the basis of phenotypic, chemotaxonomic and phylogenetic features, strain SWA25(T) should be placed in the genus Halomonas as a representative of a novel species. The name Halomonas shantousis sp. nov. is proposed, with SWA25(T)(=CCTCC AB 2013151(T) = JCM 19368(T)) as the type strain.