Females are more aggressive than males. Thats why some people have better results than others(I also think it has to do with how they were raise but I'm not an expert). Crayfish are scavengers and they will eat anything(fish, plants, and anything else they can get there claws on) so go with lotus' advice. Crayfish are really fun to watch though. Also the smaller the crayfish the less of the threat. There are dwarf blues and non dwarf blue. I think only the red,white,orange, and blues are dwarf but I'm not sure. Crayfish are NOT good community species.