As I am finding out with my first oscar, it isn't just about length...once they get around 11 to 12ish, they just bulk out in every direction. Its almost like a slow creep you don't notice right away. Then all of a sudden you can't believe how thick/big they are! When my fish was 10 inches I thought he was big. But compared to now it isn't even close...which is why I went ahead of the curve with filtration and w/cs. So far so good. Next year I may have to up the schedule, who knows.
