  We describe all polarizations for all abelian varieties over a finite field
in a fixed isogeny class corresponding to a squarefree Weil polynomial, when
one variety in the isogeny class admits a canonical liftings to characteristic
zero, i.e., a lifting for which the reduction morphism induces an isomorphism
of endomorphism rings. Categorical equivalences between abelian varieties over
finite fields and fractional ideals in \'etale algebras enable us to explicitly
compute isomorphism classes of polarized abelian varieties satisfying some mild
conditions. We also implement algorithms to perform these computations.
