I have a number of these fish. My largest is a 10 inch plus male with a large nuchal hump. Not overly aggressive, try's to throw his weight around, but backs off when someone squares up to him. There's a 7" female in his tank, but he isn't interested.
I have a smaller male around 7" who is in a tank with 2 females. Just spawned and produced fry with one of the females who he has now dumped and taken up with female number 2, which by the look of her will spawn any day now.
This male is aggressive in spawning mode, vigorously defended his brood, breaking the skin and drawing blood in 5 places on my right hand when I removed some of the fry. As others have said one of my favourites too.