The Yalosians are a spacefaring civilization. They breathe a corrosive mixture of 60% nitrogen, 10% benzene, and 30% hydrogen fluoride. They also can't perceive the red-orange part of the visual spectrum.

Deep Space 9 hosted the Yalosian ambassador in 2371. Major Kira Nerys was in charge of preparing the quarters for the ambassador. (DS9: "Improbable Cause")