  We prove the asymptotic stability of a finite sum of well-ordered solitary
waves for the Zakharov-Kuznetsov equation in dimensions two and three.
Moreover, we derive a qualitative version of the orbital stability result which
turns out to be useful for the study of the collision of two solitary waves.
  The proof extends the ideas of Martel, Merle and Tsai for the sub-critical
gKdV equation in dimension one to the higher-dimensional case. It relies on
monotonicity properties on oblique half-spaces and rigidity properties around
one solitary wave introduced by C\^ote, Mu\~noz, Pilod and Simpson in dimension
two, and by Farah, Holmer, Roudenko and Yang in dimension three.
