Esmaeilius is a genus of small toothcarps from the Middle East, with the atlas's 2 species native to Iran and Iraq. Like other Old World toothcarps in this part of their range, they are small, hardy fish of springs, streams, and marshes in an arid climate, tolerant of the wide temperature and salinity swings typical of shallow desert and semi-desert waters. They run roughly 2–2.5 in.
Data on Esmaeilius in the aquarium hobby is sparse - these are not established trade fish, and most available information comes from regional ichthyological surveys rather than fishkeeping sources. The taxonomy of the toothcarps native to Iran and Iraq has been revised repeatedly in recent years, with the old, broad genus concept split into several smaller genera, and Esmaeilius is one product of that ongoing work. Both of the atlas's species are currently listed as Not Evaluated by the IUCN.