a couple days ago i found out my 10' O was wned: by my 8' red devil.my female o had tried to defend my other o bot she was to late .by the way the o's were my first fish .so the red devil had to be evicted from the tank.
I am sorry to hear about your loss of your Oscar.. i know having them be your first fish was making the bad situation even worse.. i hope your RD gets a good home though.. they cannot help being aggressive ..and we all know they are..