Bichirs are great fish and as long as you keep then with fish that are tall bodied or over 1/2 the size of the bichir they will not eat their tankmates, i have 3 species of bichir including a delhezi and have found them to be one of the most peaceful predatory fish there are.
Michelle as sondan was hinting at all fish will eat other fish, even plecos will munch on sick fish if they cannot get away, its just what fish do and if it upsets you your in the wrong hobby