It all depends on the individual fish, my w/c female ba, the spitting immage of marks is an absolute sweetheart, she never bothers any other fish, I have just moved her in with the Rotkeils as the Elliotti were starting to give her a hard time all thats happened is she has looked at them they looked at her then went their seperate ways in the tank. Now the youngsters I have a friend had a couple one for his tank one for his dad's tank, the one his dad had is a nightmare chasing everything (it may end up back here yet!) where the other one is absolutely fine. Its the same with severums, Vinny (red spot) is a gent, so gentle and doesnt bother the other fish, where as Harry (red spot) I cant post on a family forum what sort of a devil he can be with other fish.