there might be the crayfish might try to pick on the bichir........................... maybe................ since i see lobsters and their "cusins" eat it might try to grab the bichir
I'm quite sure that more than one crayfish per tank will wind up in some battling. My pinchy also has a mean streak in him, as he regularly attacks my 12" pleco, and has already taken out other inverts, no fish however.
I foresee problems, I have had small fish beat crayfish to death but I have also had crayfish kill fish larger than they were by grabbing them by the gills.
Not a good combination... You will eventually lose one to the other, sooner or later. For now, I think the bichir can lose a piece or get seriously hurt, but it will surely eat the lobster when it grows up a bit.