  We report on the observation of Faraday waves in a cigar-shaped Fermi
superfluid of $^6$Li parametrically excited by modulating the radial trap
frequency. We characterize the phenomenon as a function of the interaction
parameter by means of a Feshbach resonance. Starting from the BEC side of the
resonance we observe a drop on the visibility of the Faraday pattern as we
approach to unitarity, possibly due to the increased incompressibility of the
system. We probe the superfluid excitation spectrum by extracting an effective
1D speed of sound for different values of the interaction parameter, in good
agreement with numerical simulations. Finally, we perform a stability analysis
in the parameter space using a simplified model and we show the emergence of
the Faraday waves as unstable solutions to a Mathieu-like equation.
