  We examine the stability of an Einstein-Maxwell perfect fluid configuration
with a privileged direction of symmetry by means of a $1+1+2$-tetrad formalism.
We use this formalism to cast, in a quasi linear symmetric hyperbolic form the
equations describing the evolution of the system. This hyperbolic reduction is
used to discuss the stability of solutions of the linear perturbation. By
restricting the analysis to isotropic fluid configurations, we made use of a
constant electrical conductivity coefficient for the fluid (plasma), and the
nonlinear stability for the case of an infinitely conducting plasma is also
considered. As a result of this analysis we provide a complete classification
and characterization of various stable and unstable configurations. We found in
particular that in many cases the stability conditions is strongly determined
by the constitutive equations by means of the square of the velocity of sound
and the electric conductivity, and a threshold for the emergence of the
instability appears in both contracting and expanding systems.
