  Two general-relativistic hydrodynamical models are considered: a model of
self-gravitating static configurations of perfect fluid and a model of steady
accretion of fluid onto a black hole. We generalise analytic results obtained
for the original polytropic versions of these models onto a wider class of
barotropic equations of state. The knowledge about the polytropic solutions is
used to establish bounds on certain characteristic quantities appearing in both
cases.
