A Gram-stain-negative, non-spore-forming, rod-shaped, obligately anaerobic bacterium, designated strain BP47G, was isolated from the hindgut of a silver drummer (Kyphosus sydneyanus) fish collected from the Hauraki Gulf, New Zealand. Phylogenetic analysis based on the 16S rRNA gene sequence of the isolate indicated that it belonged to the family Oscillospiraceae in the phylum Bacillota. The gene sequence of BP47G was most similar to Oscillibacter valericigenes with 95.23% sequence identity. Isolate BP47G grew on agar medium containing mannitol and fish gut fluid as the sole carbon sources. Clear colonies of ~1 mm diameter grew within a week at 20–28 °C (optimum 28 °C) and pH 7.1–8.5 (optimum 8.5). BP47G tolerated the addition to the medium of up to 1% NaCl. Formate and butyrate were the major fermentation products. The major cellular fatty acids were C12:0, C13:0, iso-C14:0, C16:0 and C16:1
cis 7. Genomic analyses comparing BP47G with its closest relatives indicated low genomic relatedness based on the average nucleotide identity, average amino acid identity, percentage of conserved protein and in silico DNA–DNA hybridization. Supported by the phenotypic and taxonomic characteristics observed in this study, a novel genus and species Bengtsoniella intestinalis gen. nov., sp. nov. is proposed for isolate BP47G (=ICMP 24688=JCM 35770).