On of the most interresting setups I had was an upper and a lower tank, where in the bigger upper tank I had 2 oscars. In the lower tank I kept my goldfish. Once ever couple of days, or so, I would net some goldfish and throw them in the oscar tank and watch the chase and swallow. Lots of scales floating around. Those oscars grew to about 12 inches long before I gave them to a fish store.

https://docs.google.com/spreadsheet/ccc?...amp;usp=sharing