I purchased the Tiger Oscar first and it was about 6 inches before I purchased the Red Devil. Now the Red Devil is about 12 inches and the Tiger Oscar is only 10 inches and the Red Devil is torturing the Oscar. I had to put a separating in my tank, but I don't want to keep it because it takes away from the tank and it seems each fish is crammed on one side of the tank. Any suggestions, hints, or tips on what to do? Thank You!