Nine bacterial strains designated MT3-5-12T, MT3-5-27, MTV1-9, S-DT1-15T, S-DT1-34, MTV5-3T, MTV4-17, MTV5-12 and MTV5-13 were isolated from the upper layer (1-5 cm in depth) of tidal flat sediment in Quanzhou Bay, China. The 16S rRNA gene of these strains shared maximum sequence similarities with Aestuariivivens insulae KCTC 42350T of 94.9-97.1%. Phylogenetic analyses based on 16S rRNA gene sequences and 120 conserved concatenated proteins placed these strains in three novel phylogenetic clades affiliated to the genus Aestuariivivens of the family Flavobacteriaceae. Strains MT3-5-12T, MT3-5-27 and MTV1-9 were phylogenetically close to A. insulae KCTC 42350T. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strains MT3-5-12Tand MTV1-9 and A. insulae KCTC 42350T were estimated to be 78.5-78.7% and 22.5%, respectively. Strains S-DT1-15T and S-DT1-34 formed a distinctly separated clade from A. insulae KCTC 42350T. The ANI and dDDH values between strains S-DT1-15T and S-DT1-34 and A. insulae KCTC 42350T were 76.3-76.4% and 20.4-20.5%, respectively. The other four strains MTV5-3T, MTV4-17, MTV5-12 and MTV5-13, formed a third novel clade, distinctly separated from A. insulae KCTC 42350T. The ANI and dDDH values between strains MTV5-3T and MTV4-17 and A. insulae KCTC 42350T were 74.7% and 19.1-19.2%, respectively. The phylogenetic analyses and whole genomic comparisons, combined with phenotypic and chemotaxonomic features, strongly supported the nine strains could be classified as three novel species within the genus Aestuariivivens, for which the names Aestuariivivens marinum sp. nov. MT3-5-12T, Aestuariivivens sediminis sp. nov. S-DT1-15T, and Aestuariivivens sediminicola sp. nov. MTV5-3T are proposed.