  Here we obtain all possible second-order theories for a rank-2 tensor which
describe a massive spin-2 particle. We start with a general second-order
Lagrangian with ten real parameters. The absence of lower spin modes and the
existence of two local field redefinitions leads us to only one free parameter.
The solutions split into three one-parameter classes according to the local
symmetries of the massless limit. In the class which contains the usual massive
Fierz-Pauli theory, the subset of spin-1 massless symmetries is maximal. In
another class where the subset of spin-0 symmetries is maximal, the massless
theory is invariant under Weyl transformations and the mass term does not need
to fit in the form of the Fierz-Pauli mass term. In the remaining third class
neither the spin-1 nor the spin-0 symmetry is maximal and we have a new family
of spin-2 massive theories.
