We present a model that generates small neutrino masses at three-loop level
due to the existence of Majorana fermionic dark matter, which is stabilized by
a Z2 symmetry. The model predicts that the lightest neutrino is massless. We
show a prototypical parameter choice allowed by relevant experimental data,
which favors the case of normal neutrino mass spectrum and the dark matter with
m \sim 50-135 GeV and a sizable Yukawa coupling. It means that new particles
can be searched for in future e+e- collisions.Comment: 7 pages, 3 figure