A rod-shaped, pale yellow-pigmented, aerobic, Gram-staining-negative strain with gliding motility, designated as strain SK-16T, was isolated from the coastal surface water of a semi-enclosed coastal inlet in Misaki, Japan. Analysis of 16S rRNA gene sequences revealed that SK-16T represented a member of the family Flavobacteriaceae and was closely related to the genus Algibacter, with sequence similarities ranging from 95.9 to 94.3 % to the type strains of species of the genus Algibacter. The major cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 0 G and iso-C15 : 0 3-OH. Major polar lipids were phosphatidylethanolamine, an aminophospholipid and an unidentified phospholipid. The DNA G+C content of SK-16T was 32.3 mol% and MK-6 was the only predominant isoprenoid quinone. On the basis of the results of phenotypic, genotypic, chemotaxonomic and phylogenetic studies, it was suggested that SK-16T represents a novel species within the genus Algibacter, with the newly proposed name Algibacteraquaticus. The type strain is SK-16T (=NBRC 110220T=KCTC 32974T).