yeah i mean u never know if a bichir will catch a sleeping fish one night but i wouldnt worry about it with upper jaws really. ive had 3 gouamis at about 3" in with 2 senegals and at about 9" and a koliba at 10" and the for a while and they are fine. howevr i have a 40 breeder growing out a couple of 4-5" ornates a 5" albino sen and a 4" endli and my gf threw some new baby bowfin in with them cuz apparently i didnt tell her to put them in another tank and only 1 bowfin survived by the time i got home from work so.... theres always a chance. but most of the time i would think you would be fine with that. nothing is for sure in fish keeping.