  We discuss dissipative processes in strongly gyrotropic, nearly collisionless
plasma in clusters of galaxies (ICM). First, we point out that Braginsky
theory, which assumes that collisions are more frequent that the system's
dynamical time scale, is inapplicable to fast, sub-viscous ICM motion. Most
importantly, the electron contribution to collisional magneto-viscosity
dominates over that of ions for short-scale Alfvenic motions. Thus, if a
turbulent cascade develops in the ICM and propagates down to scales $\leq 1$
kpc, it is damped collisionally not on ions, but on electrons. Second, in high
beta plasma of ICM, small variations of the magnetic field strength, of
relative value $\sim 1/\beta$, lead to development of anisotropic pressure
instabilities (firehose, mirror and cyclotron). Unstable wave modes may provide
additional resonant scattering of particles, effectively keeping the plasma in
a state of marginal stability. We show that in this case the dissipation rate
of a laminar, subsonic, incompressible flows scales as inverse of plasma beta
parameter. We discuss application to the problem of ICM heating.
