As long as the pike will not fit in the Bichir's mouth or the bichir in the pike's mouth you should be fine. I have 9 pikes and 12 Bichirs in a 185 and they pretty much just ignore each other. They are all growing so it may change in time.
even though they have similar body shapes, they usually get along better (at least in my limited experience) than crens do with other crens and other cichlids.