  We study the general fibre of a formal deformation over the formal disk of a
projective variety from the view point of abelian and derived categories. The
abelian category of coherent sheaves of the general fibre is constructed
directly from the formal deformation and is shown to be linear over the field
of Laurent series. The various candidates for the derived category of the
general fibre are compared.
  If the variety is a surface with trivial canonical bundle, we show that the
derived category of the general fibre is again a linear triangulated category
with a Serre functor given by the square of the shift functor.
