My severums are only agressive with each other. The red head female is the worst, I had to take my male gold out of the tank because she wouldn't even let him eat.
My sevs in the past haven't been too bad, but the gold male I have now is the biggest jackass ever. He's not even full grown - right now he's about 6". Had him since he was about 2.5". I first got him and put him in my SA community tank with a MUCH bigger S. daemon and some other larger fish. Finally had to move him and put him into a tank with the slightly bigger goldsaum breeding pair and convict male because he was such a jerk to everyone in his other tank. He held his own for a couple months, maybe less, before I noticed the convict male (about 3.5" to the gold sev's 4") hiding in the corner. Chester (the sev) beat him to **** and he died a couple days later. Then he started beating on the goldsaum pair. I just removed the female the other day. I tried adding two more green sevs since I didn't want one sev in the tank by himself...he beat the snot out of the bigger guy and I had to remove him, but is allowing the smaller one to hang out with him. I'm assuming it's a female. If the little jackass wasn't so freaking gorgeous, I'd get rid of the bastard.