cichlid wise i'm gonna say no... probably a large pleco that can take some hits at the most.
why not just rear a nice show quality fish that's free of scrapes and nicks.
You can try some type of bottom dweller. Maybe some smaller archocentrus, or thorithcys type fish that the zonatum might not fell threatened by so might not kill if they have hide spots.
Yeah I have seen some large zonatum and have heard they are VERY mean. They are beautiful fish though. But in a 90 I wouldn't try any other cichlids. Possibly a pleco or some bigger loaches.