Here's mine. He's about 8-9".
They never actually fight, they just flex in front of each other once in a while. It never comes to blows.That's about as far as it gets in that picture.
(Notice no missing scales or torn fins)
He mostly keeps to himself. He has a good temperment and mostly hangs out in or around his log. Most Dempseys are like that, so dont expect a super personable fish that swims non-stop around the tank. They tend to keep stationary until feeding time.
(there are always acceptions though.)