the silver tip is about 6" the oscar was about the same, but of course larger, as the oscar is a deeper and thicker fish. They lived in a 60 gal.
The silver tip had always left the oscar alone unless it got too close, but the last month or so the silver tip has been chasing everything that moves. My guess is the oscar thought it was too tough to back down... whoops.
The bright side of the train wreck is that my impulse buy arowana is now living in that tank. He was cooped up in a 10 gal. Since he stays at the top of the tank, he and the silver tip haven't had any run-ins just yet, hopefully things stay that way.
Of course I'm getting a bigger tank for the aro soon.