  We investigate the strongly interacting regime in an optically trapped $^6$Li
Fermi mixture near a Feshbach resonance. The resonance is found at $800(40) $G
in good agreement with theory. Anisotropic expansion of the gas is interpreted
by collisional hydrodynamics. We observe an unexpected and large shift ($80 $G)
between the resonance peak and both the maximum of atom loss and the change of
sign of the interaction energy.
