He's apparentley the Alpha-male. If he is a vicious dictator I would take him to the lfs and trade him in.
I have found that once an Alpha tastes blood the carnage continues. Observe your flock and see who, in the absence of the Zebra would be the next contender for the Alpha's spot. Observe the tank for a while and see who goes where and when. As was mentioned if you don't have enough caves, shelters, open space for your particular species then fights can erupt. When I say fights I mean more than just a shuttering or quick mouht tug.
Just take your time and observe. Keep us posted.
Row well and live.
55g mixed Haps, mbuna, syn eup, Syn ?
125g mixed Haps, Labs, Syn multis, N. Ven, P. Phinoc, C. Moorii, Exo. anyg, Assorted Peacocks,accei, Red Emp