None of them are chasing or seem territorial, and the fins all look similar. I am not sure how to tell the difference unless the male is in breeding condition.
They're too young to be colored up yet, so it's impossible to tell. If you have room, it's normal to just buy a bunch and rehome the unwanted ones once they grow up. Otherwise it's your best guess. One male to two females can work pretty well, too.
I'll just get the whole lot, then. I'll put them in the 30 gallon for QT and move them to the main tank in 2 weeks. Then actually put the fish I want in the 30 gallon in there.