my oscars are constantly fighting. just keeping an eye on them throw in some melefix from time to time to help with healing you can also try and lower the temp in the tank a little something clams them down
like someone else said, put some distraction in there. id add a trio of silver dollars, rearrange the tank and see what they do. you may need to separate them if they are damaging eachother..
This is completely untrue... I've had Oscars kill each other... and I've had Oscars kill other fish... it is silly to think an Oscar cannot kill another Oscar...