  We apply fluctuating hydrodynamics to strong electrolyte mixtures to compute
the concentration corrections for chemical potential, diffusivity, and
conductivity. We show these corrections to be in agreement with the limiting
laws of Debye, H\"uckel, and Onsager. We compute explicit corrections for a
symmetric ternary mixture and find that the co-ion Maxwell-Stefan diffusion
coefficients can be negative, in agreement with experimental findings.
