dont get a male they i think are more aggressive and i had a few crays in a 10g by themselves they're super cool they devour rosy reds its awesome! mine rarely caught their own food though so u gota hand feed them ocasionaly lol make sure u get them with the proper fish and ive heard they eat live plants never had a chance to test that tho dont get a huge crayfish my friend has a monster 5 incher we caught in a creek and we put that in a tank along with a retarted looking shad and the crayfish climed up onto a fake plant and hovered then jumped onto the shad and ate the whole thing and it was about 6 inches long so be careful