My tank has been set up less than 6 weeks and I have been moving everything around trying to aquascape. I started with 3 smaller cardinals then after a bout 2 weeks, one started to get beat on and separated from the other 2. I removed him and all was fine. The other 2 get along great, but often are at least half the tank away from each other (125g). Now they are together in a little cove and the male has a mouthful!