The isolates have streamlined circular genomes with sizes between 1.37 and 1.44 Mb, low GC content for Actinomycetota, ranging from 43.3 to 45%, and high coding densities ~95.6%. All isolates encode one rRNA operon and between 37 to 42 tRNA genes. They are auxotrophic for some amino acids and vitamins. They encode for actinorhodopsins, heliorhodopsins, and the biosynthesis pathway of the retinal. Recruitment analysis of 1720 metagenomes suggests that Aquilimus members are not particularly abundant, although some species are distributed on different continents and seem to be constantly recovered throughout the year, at least in the case of the Římov Reservoir (Czech Republic). The current GTDB classification (r220) is d__Bacteria;p__Actinomycetota; c__Actinomycetes;o__Nanopelagicales; f__Nanopelagicaceae;g__AAA044-D11.