I have 3 severums. They don't like blood parrots and the parrots don't like them either. I have plenty of rock work in the tank with loads of caves and tunnels, so there's enough hiding places to make sure none of the chasing ends in bloodshed.
Neither the severums nor the blood parrots show significant aggression towards mbuna or catfish, so it seems like the aggression is directed towards fish with similar body shapes.
