A Gram-negative, facultatively anaerobic, moderately halophilic bacterium, strain ND1-1(T), was isolated from fermented fish (pla-ra) in Thailand. The cells were curved rods, motile and non-endospore-forming. The novel strain grew optimally at 37 degrees C, at pH 8 and in the presence of 9-10 % (w/v) NaCl. The predominant respiratory lipoquinone was Q-8. The major cellular fatty acids were C(16 : 0) and C(12 : 0). Polar lipid analysis revealed the presence of phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The DNA G+C content was 49.0 mol%. Comparative 16S rRNA gene sequence analyses indicated that strain ND1-1(T) was closely related to Salinivibrio costicola, which comprises three subspecies, and Salinivibrio proteolyticus with gene sequence similarities of 98.3-98.6 %. Strain ND1-1(T) showed low levels of DNA-DNA relatedness with S. costicola subsp. costicola JCM 15095(T) (33.2 %), S. costicola subsp. alcaliphilus DSM 16359(T) (38.4 %), S. costicola subsp. vallismortis JCM 15096(T) (59.7 %), and S. proteolyticus AF-2004(T) (42.1 %). On the basis of the physiological and biochemical characteristics and the molecular data presented, strain ND1-1(T) should be classified as a novel species of the genus Salinivibrio for which the name Salinivibrio siamensis sp. nov. is proposed. The type strain is ND1-1(T) (=JCM 14472(T)=PCU 301(T)=TISTR 1810(T)).