The Volus are one of the species in the Mass Effect games. They have an embassy on The Citadel which they share with the Elcor. The Volus are experts on finance and are usually used as bankers and financial consultants. They also created the currency of credits that the galaxy uses.
Early on in their history, the Volus formed an alliance with the Turians, trading their ability to handle complex economics for the Turians military protection. While they still maintain a good relationship with the Turians they are now a Citadel species with their own embassy. The Volus' main duty is to manage the complex and delicate Citadel economy, but many Volus can also be seen in the market section of the Wards, selling all kinds of goods. The Volus most important contribution to Citadel society is the Unified Banking Act, which created one bank for all Citadel species, and more importantly, one currency for all Citadel species. Many people in the Citadel believe that if humanity gets a council seat, the Volus will get one as well. However, the main reason the Volus do not have a member on the council is their inability to supply resources and fleets in times of need.
The Volus hail from the planet Irune, and they must wear pressure and environment suits when travelling away from their homeworld. Irune is an unusual planet, lying too far away from any one star to be able to support life. Irune has a high pressure atmosphere though, which creates a very powerful greenhouse effect that traps enough heat from the closest star to warm the planet and create an ammonia based atmosphere. Because ammonia is such an unusual gas to breathe, any exposure to an oxygen based atmosphere will literally cause a Volus' skin to begin splitting apart. While a member of the Citadel, on Irune the Volus still maintain a tribal culture, where status is dependent on how good of a merchant you are. Always looking to get ahead, the Volus will also dabble in slave trading or other distasteful acts that they feel are necessary in order to move up in the social hierarchy.