I don't have him any longer, but I never experienced aggression problems from him. I made another thread about this a little while back with some videos:Do you still have this jar and does he try to beat up the other fish?
Changing up my tanks a little - advice on stocking
Wise words Joe. You are right in that its the most logical and best option long term. The Geos and SDs would be really happy. I just feel a little "empty" inside myself when I think of getting rid of my Jar. He has grown so much, and he does have such a great personality. I was going to...
www.monsterfishkeepers.com
Quoted the relevant part below pertaining to your question:
"So just an update on the above.
Two days ago I had 9 x Silver Dollars, 7 x Geophagus Tapajos, 1 x Jardini aro (I thought my Jar was around the 32 - 34cm mark, turns out he was closer to 40cm when I actually moved him out the tank) in my 720L aquarium.
As briefly discussed above it was suggested the Jar may need to be rehomed due to aggression issues. This turned out to be true, but not as you would think.
The aggressive fish in this case turned out to be the silver dollars.
My Jar was quite placid, and hasn't ever troubled any of his tank mates. Until about two weeks ago I started to see my SD's nipping at his fins, and he was slowly getting more and more damaged. Eventually the poor guy bashed himself into a rock and damaged his eye trying to swim away from them, and then it seemed like the SDs were starting to go after his gills for some reason. They too were looking ragged.
Eventually my Jar was hardly eating, and stayed in the bottom corner of the tank whilst the SDs and geos had full run of the tank.
The geos remain untouched as often the SDs like to shoal together with them. Making it near impossible for the Jar to fight back against any single target. I will post a video of them soon, I cannot believe how thick the SDs have become. My thickest is approx. 2.5cm now (must be all the shrimp they were stealing from the aro haha)"