in my experience they absolutely love them, if you're worried about htem hurting the bichirs wait for the crayfish to molt and toss em in right afterwards
in size they are like 1/4 or smaller than the size of my bichirs head and are smaller than pinhead crickets if anyone has feed those to their fish or reptiles
well i put three in there and immediately my yoyo loach started chasing them but i think the bichir managed to get one because he was chomping down on something and there was no other food in the tank, so only time will tell if this was a bad idea
well the crawfish have been a feeding success, even after eating one of my baby plecos<1" he has been chowing down on about 5(that i have counted) crawfish and is still going... i have a feeling he will be a future money pit
I would think they would be safe just don't put a large crayfish with the bichir just something they can easily handle. I'm raising marbled crayfish just for that purpose. In the wild studies show they eat crabs ( I didn't know that) so a crayfish isn't that much of a difference!