A Gram-stain negative, facultatively anaerobic, rod-shaped, non-motile and non-spore forming bacterium, designated ZS-11(T), was isolated from an artificial freshwater lake in Guangzhou city, Guangdong province, China. Growth of strain ZS-11(T) was observed at the temperature 18-42 degrees C (optimum 32-37 degrees C), pH 6.0-8.0 (optimum 7.0) and 0.5-3.0% (w/v) NaCl (optimum 0.5%, w/v), and also found to be enhanced in the presence of CO2. Pairwise comparison of 16S rRNA gene sequences showed that the strain shared high similarities with Serratia entomophila DSM 12358(T) (96.1%), Serratia ficaria DSM 4569(T) (96.0%), Serratia plymuthica DSM 4540(T) (96.0%), Rahnella victoriana FRB 225(T) (95.9%) and Rouxiella badensis DSM 100043(T) (95.8%). The phylogenomic dendrograms showed that strain ZS-11(T) formed a distinct cluster within the clade of the genus Serratia. The major fatty acids (> 20%) present in the cells were C-16:0, C-16:1 omega 7c/C-16:1 omega 6c and C-18:1 omega 7c/C-18:1 omega 6c, which were consistent with those of S. entomophila CCUG 55496(T) and Serratia liquefaciens CCUG 9285(T). The DNA G + C content for the genome was 49.3%. Based on these phenotypic and genotypic data, strain ZS-11(T) is considered to represent a new species of the genus Serratia, for which the name Serratia microhaemolytica sp. nov. is proposed. The type strain is ZS-11(T) (= CCTCC AB 2018040(T) = KCTC 62413(T)).