for the bichir
i was gone for a few hours and when i got back i noticed that there were 2 minnows that were missing tails. but i dont see why the bichir would try to eat the minnows when there are smaller guppies with him.
They are opportunistic predators, was prob just as likely to be the guppies. They are probably missing tails because your bichir couldn't seal the deal
Birchirs will take a chunk out of their food, and use them wonderfully long nasal tubercels to search out the wounded fish and finish it off when its weak. As for the minnow yes it is normal some fish can sustain huge amounts of damage and carry, but i dont think this one will get chance!