It's funny you mention saltwater. I was thinking that once the Oscar got too big for this tank, I would return him and make an attempt at a saltwater tank. The best part about saltwater is that it's difficult to overstock it due to the cost involved. It's so easy to overstock a tank when some fish literally cost a dollar a piece.
That brings me to another point. I think that fish stores should charge more for their freshwater fish. Not quite as much as saltwater, but if they charged more, there would be higher profit on each fish, and it would discourage people from unintentionally overstocking their tank.
And why would I want to return my other fish? They're going to be Oscar food. I like watching him eat. He ate right out of my hand today. I'm really liking Oscars. They aren't the most attractive fish out there, but they really have personalities.