dino eel, he is refering to the name somtimes given to bichirs in unknowing LFS, Personally i am a big Fan of bichirs myself having 2 4.5"-5" albino polypterus senegalus and previously Owning a Polypterus Delhezi,
they are astounding fish to watch, i always compare them to otters, in their movement towards the glass when they swimming arround. Though Bichirs are Carniverous and love to eat their meat "mine go crazy for it" they can take pellets and smaller granulated foods when small, i dont know as they grow bigger, but i expect their diet should stay the same. With some sorts of Bichirs such as Delhezi they only eat live,"to my experience" my one never touched pellets. As long as the bichirs have alot of places to hide they wont bother eachother, my guess is that Penelope was exploring the caves or hiding places and ran into Einstein, and hes just thought "i wonder what this is?" and chomp, either install more places to hide or keep them separate as they are quarrel some with eachother and if their is a size difference it can really show in them arguments. i guess installing some caves for them to hide.
i hope i have helped.