  Under the hydrodynamic equilibrium Buchdahl's conditions on the behavior of
the density and the pressure, for regular fluid static circularly symmetric
star in (2 + 1) dimensions in the presence of a cosmological constant, is
established that there are no bounds from below on the pressure and also on the
mass, except for their positiveness. The metric for a constant density
distribution is derived and its matching with the external static solution with
a negative cosmological constant is accomplished. Some mistakes of previous
works on the topic are pointed out.
