Members of the '''Fire Caste''' are the warriors of the [[Tau Empire]], and as such are most often seen on the field of battle. They have been bred to be the tallest, strongest, and most aggressive Tau, and weak strains are quickly weeded out. These traits come from the Fire Caste's origin on the plains of [[T'au]], where they were hunters and warriors. [[Fire Warriors]], as soldiers of the Fire Caste are known, spend their entire lifetimes in battle or preparing for it, constantly honing their tactics and working to improve their skills. Tau from the world of [[Vior'la]] tend to have slightly greater muscle mass than the norm because of the stronger gravity of that planet.{{Fn|6a}} The Fire Caste guided by the [[Code of Fire]] - a doctrine of loyalty, martial arts and merciless war tempered by wisdom.{{Fn|6a}}{{Fn|99a}}

The Water Caste serve the Tau Empire as traders, merchants, public servants, bureaucrats, administrators, diplomats, and ambassadors. They interact with other races when such affairs are not handled by the Fire Caste, and often act as administrators of Tau worlds in the absence of an [[Ethereal]] governor. Like water, Water Caste bureacrats fluidly move between other Castes and alien races incorporated within the Empire to make sure that it flows smoothly. The Water Caste tend to be tall and slender compared to other Tau, and are known for their great linguistic, diplomatic, and negotiation skills. Members of the Water Caste are often the ones who initiate first contact with new species encountered by the Empire, skilfully negotiating their union with the Tau.{{Fn|6a}} The members of the Water Caste has a gift for linguistics that has become more and more developed over time, so they able to learn alien languages with ease and show a remarkable ability to emulate and pick up subtlest of communication features.{{Fn|99a}}

*{{Endn|9}}: [[Codex: Tau Empire (7th Edition)]], **{{Endn|9a}}: ''The Castes''**{{Endn|9b}}: ''Alien Auxiliaries''