How aggressive do your Flyers get when they decide to breed? Under most circumstances I would say that you could easily house 3 or 4 Polypterus senegalus in a standard 60 gallon tank but personally I try to avoid keeping my bichirs with aggressive cichlids, especially those that are breeding pairs. After all, spending most of their time at or near the bottom, bichirs would likely appear threatening to substrate-spawning cichlids that defend their eggs, much to the detriment of the bichirs. There are those who have kept bichirs and big cichlids together successfully but I've heard too many horror stories about what happens when things go bad and the cichlids go on a rampage.
-Joe
