  Using the AdS/CFT correspondence, we calculate a fermionic spectral function
in a 2+1 dimensional non-relativistic quantum field theory which is dual to a
gravitational theory in the $AdS_4$ background with a charged black hole. The
spectral function shows no quasiparticle peak but the Fermi surface is still
well defined. Interestingly, all momentum points inside the Fermi surface are
critical and the gapless modes are defined in a {\it critical Fermi ball} in
the momentum space.
