Unfortunately, that's what they do naturally. It's recommended to community them only with short-finned fish.
If you are going to keep them together, I would recommend getting something to help their healing when they do get bitten a little too much. It will stop eventually if the finned fish get big enough to defend themselves.
Yeah, you're pretty much seeing the extent of their "bad side." You should see them when they're pregnant, though! They get truly aggressive then