We investigate the effect of anisotropies in the fermion velocities of 2+1
dimensional QED on the critical number N_f^c of fermions for dynamical mass
generation. Our framework are the Dyson-Schwinger equations for the gauge boson
and fermion propagators formulated in a finite volume. In contrast to previous
Dyson-Schwinger studies we do not rely on an expansion in small anisotropies
but keep the full velocity dependence of fermion equations intact. As result we
find sizable variations of N_f^c away from the isotropic point in agreement
with other approaches. We discuss the relevance of our findings for models of
high-T_c superconductors.Comment: 9 pages, 7 figures, v2: minor changes, typos corrected, version
accepted by PR
