Type genome is Fontibacterium universale N-InaE-25sep22-010 (GCA_965236175.1), a metagenome-assembled genome (MAG) assembled from 5 m depth from Lake Inawashiro, Japan (date: 2022-09-25). N-InaE-25sep22-010 has a genome size of 1.0 Mbp with a genomic GC content of 29.3% and contains 29 tRNAs. The genome is of high quality, consisting of 4 contigs, with a completeness of 98.8%, contamination of 0% and strain heterogeneity of 0% as assessed with checkM. The metagenome was assembled with FLYE from combined long-and short-read sequencing (Oxford Nanopore and Illumina NovaSeq). Metagenomic fragment recruitment of >600 samples from five continents indicate that the species is present in many lakes around the world. The closest cultivated relatives are Fontibacterium commune, syn. ‘Candidatus Fonsibacter ubiquis’ LSUCC0530 (GCF_002688585.1; later reclassified to ‘Ca. Allofontibacter communis’), with an average amino acid identity of 87.08% and average nucleotide identity of 85.18% and another newly proposed species, Fontibacterium abundans MiE-29 (GCA_965235095.1), with an AAI of 92.44% and an ANI of 90.87%. Current GTDB classification (R220): d__Bacteria; p__Pseudomonadota; c__Alphaproteobacteria; o__Pelagibacterales; f__Pelagibacteraceae; g__Fonsibacter; s__Fonsibacter sp000371845.