A Gram-stain-negative, yellow, non-spore-forming, strictly aerobic bacterium, designated C3T, was isolated from a cyanobacterial culture pond. Cells were halophilic, rod-shaped and able to move by gliding. Growth of strain C3T was observed at 15-30 °C (optimum 25 °C), pH 6.0-9.0 (optimum pH 7.5), and in the presence of 1-7 % (w/v) NaCl (optimum 2-3 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain C3T formed a distinct lineage within the family Flavobacteriaceae and exhibited the highest similarity (95.21 %) to the type strains of Maribacter dokdonensis, Maribacter arcticus, Maribacter orientalis and Maribacter stanieri, and 'Maribacter caenipelagi' HD-44. The only isoprenoid quinone present within strain C3T was menaquinone 6 (MK-6). The G+C content of genomic DNA was 41.5 mol%. The major polar lipids were phosphatidylethanolamine and three unidentified lipids. The predominant cellular fatty acids (>5 % of the total fatty acids) were iso-C15 : 1 G, iso-C15 : 0, iso-C15 : 0 3-OH, iso-C17 : 0 3-OH, and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c). On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, strain C3T represents a novel species of the genus Maribacter, for which the name Maribacter flavus sp. nov. is proposed. The type strain is C3T ( = KCTC 42508T = CGMCC 1.15112T).