I used to have 4 Oscars that are around 6 years old. I could like to know how old is your Oscar before they die. I know they could live to 10 years old if they are well taking care of in an aquarium.
Mine which is a BEAST BTW is about 4 months old. I got him/her in October from Jack's Aquarium & Pets by my place and fought with him through some early illnesses (much water changes and some MelaFix did the trick though)