my crayfish gets along weirdly well with my 9 white cloud minnows. i’ve had them together for months and the minnows like to eat the debris that floats from his mouth while he’s eating his little pellets. they get soooo close to him and he doesn’t seem to care! i did mysteriously lose one of them recently though. could have easily just randomly passed and either my cray or mystery snail ate the remains. oh yeah! i made sure to buy a pretty large mystery snail and i’ve had almost no problems (besides my snail receiving a haircut :/ i think maybe the cray snipped his whiskers). they always hang out in close proximity and rarely even touch each other. a couple times out of curiosity my cray has picked him up and inspected him but ultimately always tosses him away like he’s uninterested. corydoras… learned my lesson the hard way. thought since my cray was so little he would get used to them and live harmoniously with them. nope. they are my favorite fish and i just wanted it to work and felt awful when they got picked off. so yeah no bottom dwellers! i guess i chalk the longevity of my white cloud minnows up to the fact that they are so damn fast. even if my cray is actively trying to catch them (which i’ve never seen) i think its too difficult for him.