  We extend the scaling relations of stably stratified turbulence from the
geophysical regime of unity Prandtl number to the astrophysical regime of
extremely small Prandtl number applicable to stably stratified regions of stars
and gas giants. A transition to a new turbulent regime is found to occur when
the Prandtl number drops below the inverse of the buoyancy Reynolds number,
i.e. $PrRb<1$, which signals a shift of the dominant balance in the buoyancy
equation. Application of critical balance arguments then derives new
predictions for the anisotropic energy spectrum and dominant balance of the
Boussinesq equations in the $PrRb\ll1$ regime. We find that all the standard
scaling relations from the unity $Pr$ limit of stably stratified turbulence
simply carry over if the Froude number, $Fr$, is replaced by a modified Froude
number, $Fr_M\equiv Fr/(PrRb)^{1/4}$. The geophysical and astrophysical regimes
are thus smoothly connected across the $PrRb=1$ transition. Applications to
vertical transport in stellar radiative zones and modification to the
instability criterion for the small-scale dynamo are discussed.
