Let me tell you. I love oscars. So much personality and different personalities. I like the comment in another post by cigars. He keeps oscars with his other big fish to sort of keep order in the tank. At least that's what I got from it.Some of mine don't like me poking around in the tank either, substrate cleaning and such, but they enjoy the fresh water. It makes me like doing their water changes.
As you say they love the clean water. They super love food. At least mine do. Only about 7 months old give or take.
And no grudges with these fish. Squabble here and there. Defend themselves from pbass sometimes but otherwise just happy fish.