  We study a three-components fermionic gas loaded in a one-dimensional optical
trap at half-filling. We find that the system is fully gapped and may order
into 8 possible phases: four 2$k_F$ atomic density wave and spin-Peierls phases
with all possible relative $\pi$ phases shifts between the three species. We
find that trionic excitations are unstable toward the decay into pairs of kinks
carrying a {\it fractional} number, $Q=3/2$, of atoms. These sesquions
eventually condense upon small doping and are described by a Luttinger liquid.
We finally discuss the phase diagram of a three component mixture made of three
hyperfine level of $^6$Li as a function of magnetic field.
