i thnk i have a wierd case with my 18" pim.... he has YET to eat another fish in my tank that I have sen.... And I have a few fish in the tank less then 3", including a powder blue gourami that came with my tank about 2 years ago that refuses to die... lol There is at least 3 or 4 fish in the tank he could very easily fit in his mouth, and have been others... just have yet to see it happen!
I had a RTC that was like that. He would NEVER eat another live fish. He was over 2' and lived in a community tank. He once swallowed a 2" redtailed shark by mistake when he was sucking up a piece of smelt and spit him out