We had 6 of them for three years before we had to take the tank down for moving. Yes, they pretty much chased each other around the tank, with the largest one the most agressive. It looked like they were nipping at each other, but in the three years, we never saw any fin damage and we were watching that pretty closely. We also had three congo tetras in the same tank and they did the same thing to each other. But neither species was observed "nipping" at any other species but there own.
I've found it to be very peaceful. I only have one in the tank,as he is a donation! Keeps mainly to the bottom half of the tank any no trouble at all. No fish in this tank have nice long flowing tails, which might help.