A Gram-stain-negative, rod-shaped, non-spore forming, motile and strictly oxidative bacterium, strain CHU3T, was isolated from fresh water in the Daecheong Reservoir, South Korea. A comparison of the 16S rRNA gene sequence showed that the novel bacterium is closely related to Paucibacter toxinivorans 2C20T (=KCTC 42569T) with a sequence similarity value of 97.8 %, Pelomonas saccharophila DSM 654T (=KCTC 52256T) with 97.4 % similarity and Pelomonas aquatica CCUG 52575T (=KCTC 42961T) with 97.3 % similarity, respectively. The major fatty acids (>10 %) of the isolate were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. Ubiquinone-8 was detected as the respiratory quinone. The polar lipids contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine and an unidentified aminolipid. The DNA G+C content was 62.5 mol%. DNA-DNA hybridization experiments with PaucibactertoxinivoransKCTC 42569T (=2C20T), PelomonassaccharophilaKCTC 52256T (=DSM 654T) and PelomonasaquaticaKCTC 42961T (=CCUG 52575T) resulted in relatedness values of 20 % (reciprocal 11 %), 16 % (reciprocal 17 %) and 15 % (reciprocal 19 %), respectively. The phylogenetic analysis, DNA-DNA hybridization value, polar lipids, fatty acid composition and other physiological characteristics confirmed that strain CHU3T represents a novel species in the genus Paucibacter for which the name Paucibacter oligotrophus sp. nov. is proposed. The type strain is CHU3T (=KCTC 42519T=CICC 24092T). An emended description of the genus Paucibacter is also proposed on the basis of new data obtained in this study.