I will describe an infinite family of novel hydrodynamic theories, describing the universal effective theories of thermalization in many-body chaotic systems with fracton-like mobility constraints. Examples include fluids where charge and dipole moment are both conserved, and where charge is conserved along every line or plane of a lattice. These mobility constraints can be microscopic or arise from an emergent symmetry at long wavelengths. I will show that subdiffusion in a cold atomic gas in a tilted optical lattice, as well as subdiffusion of a charged fluid in a uniform background magnetic field, can both be understood as immediate consequences of our general formalism.