  When continuous rotational invariance of a two-dimensional fluid is broken to
the discrete, dihedral subgroup $D_6$ - the point group of an equilateral
triangle - the resulting anisotropic hydrodynamics breaks both
spatial-inversion and time-reversal symmetries, while preserving their
combination. In this work, we present the hydrodynamics of such $D_6$ fluids,
identifying new symmetry-allowed dissipative terms in the hydrodynamic
equations of motion. We propose two experiments - both involving high-purity
solid-state materials with $D_6$-invariant Fermi surfaces - that are sensitive
to these new coefficients in a $D_6$ fluid of electrons. In particular, we
propose a local current imaging experiment (which is present-day realizable
with nitrogen vacancy center magnetometry) in a hexagonal device, whose
$D_6$-exploiting boundary conditions enable the unambiguous detection of these
novel transport coefficients.
