Hi all, I am new to discus (5 months ). These are beautiful fish, but such bullies. I have had 6 discus in my 180 lt tank. Sizes one 6" four 4-5" and a 3". The pidgeon, panda, melon and blue diamond are the bullies. The leopard and yellow crystal the bullied. A week ago I found them using the yellow crystal like a football, head butting it all around the tank, It ended up unable to swim upright. I put it in a salted quarranteen tank for protection, unfortunately it did not survive. The leopard which has been bullied from the start continues to get battered. It has survived I think because it is the second biggest in the tank. Without the crystal to bully they seem to be picking on it more and more. My question is how do I stop it, or do I have to remove it from the tank?