  A correspondence between scalar field fluctuations and generalized
fluctuations in a hydrodynamic approximation of fields is obtained. The results
presented here are of interest to field-fluid correspondences and form part of
theoretical foundations in this area. The intention for such developments is to
explore sub-hydro range mesoscopic physics for the relativistic fluids in
curved spacetime. The fluid correspondences fall in the classical domain and
can replace the quantum fields and fluctuations for scales around the
hydrodynamic limits.The present article extends our earlier results with a more
elaborate physical insight towards the quantum fluids and retention of partial
quantum nature in a stochastic description in bulk of the fluids. This also
accounts for non-thermal effects along with thermal and quantum fluctuations
for the fields in the hydro limit. Hence the expressions presented here are
very general in nature for various applications. The further scope of research
that such developments give is discussed in the concluding section.
