I would say that the big one and the small on e with the black, are male(big) female( smallw/ black). Of all of the carps that i have had The females in a mixed community, like yours, would have the black chin. As for the devil and single carp, I have no idea. I've never had any luck at sexing red devils and singlual carps are an issue for me unless i see them in the tank in person because some females will not get the black blotch on the dorsal until way later in life if there is no male present. I'll take a guess though and say it's a male becaause of the head being taller and more bulldog like then any of the females i've had.
Of course you will not know for sure until someone starts breeding or laying egss.
