As aforementioned, they are model citizens 99% of the time. And the other 1% of the time they are breeding or guarding eggs and can get a bit nasty. I have mine in with some pristella tetras and some bronze cory's. The Cory's are large and can take some abuse but they tend to stay away from the kribs at all cost. Nothing ever becomes of it because if the kribs even look at the corys they swim away. Is your aquarium planted? If not, planting it can create natural barriers and reduce aggression. I love my kribs; they are very entertaining. You won't regret it.