This hypothesis starts from considering the physical vacuum as a superfluid quantum medium, that we call superfluid quantum space (SQS), close to the previous concepts of quantum vacuum, quantum foam, superfluid vacuum etc.[1, 2, 3] We usually believe that quantum vacuum is populated by an enormous amount of particles pairs (e.g. couples \mathrm{e^{-},\,e^{+}}) whose life is extremely short, in a continuous foaming of formation and annihilation. Here we move further and we hypothesize that these particles are superfluid symmetric vortices of space's quanta (SQ, for which we use the symbol \varsigma), probably arising as perturbations of the SQS through a process similar to that of a Kármán vortex street, where dark matter probably acts as perturbing element. Because of superfluidity these vortices can have an indeterminately long life. Vorticity is interpreted as spin (particles' internal motion) and when two vortex-particles possess conflicting vorticity they destroy each other, justifying matter-antimatter annihilation. SQS would be an ubiquitous superfluid sea of SQ, before being a foam of particles pairs. Due to its non-zero viscosity, these vortices attract the surrounding quanta, pressure decreases and the consequent incoming flow of quanta, radially directed toward the center of the massive particle lets arise a gravitational potential. This is called fluid quantum gravity, whose passive quantum is the SQ and the quantum potential is triggered by the spin of any massive particles. We don't need gravitons in this model. We immediately notice that such a fluid model perfectly matches Gauss's law for gravity and this has been indeed proven through CFD simulations. Once comparing fluid quantum gravity with general relativity, it is evident how a hydrodynamic gravity can fully account for the relativistic effects due to spacetime distortion, where the space curvature is substituted by flows of space's quanta through the SQS. Also special relativity can be merged in the hydrodynamic of a SQS and we obtain a simplification of Einstein's relativity under the single effect of fluid quantum gravity.