  Recently the interest in relativistic quantum plasma is increasing primarily
to understand the fundamentals of the plasma behaviour and its properties.
Mathematical models used to investigate these plasma are still need to be
matured. Especially, the relativistic quantum electron-ion plasma are modeled
using the Klein-Gordon equation and the Dirac equation for relativistic
electrons. However, different properties of these plasma are investigated
without anti-particles. We note that in order to preserve causality
relativistic quantum plasma must contain anti-particles for relativistically
dynamical components of the plasma.
