Type genome is Fontibacterium scandinaviense AM1_bin-0028 (GCA_903869725.1), a metagenome-assembled genome (MAG) assembled from 0.5 m depth from Lake Alinen Mustajärvi, Finland (date: 2015-08-8). AM1_bin-0028 has a genome size of 1.1 Mbp with a genomic GC content of 28.9%, contains 3 rRNA genes and 31 tRNAs. The genome is of high quality, consisting of 55 contigs, with a completeness of 100%, contamination of 0% and strain heterogeneity of 0% as assessed with checkM. The metagenome was assembled with Megahit (version 1.1.13) from short-read sequencing (Illumina MiSeq). Metagenomic fragment recruitment of >600 samples from five continents indicate that the species is mainly present in boreal lakes in Scandinavia. 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 72.71 % and average nucleotide identity of 75.18 % and another newly proposed species, Fontibacterium abundans MiE-29 (GCA_965235095.1), with an AAI of 73.3 % and an ANI of 75.56 %. Current GTDB classification (R220): d__Bacteria; p__Pseudomonadota; c__Alphaproteobacteria; o__Pelagibacterales; f__Pelagibacteraceae; g__Fonsibacter; s__Fonsibacter sp903869725.