I have fry about 3 weeks old four are like pinkish colored and one is a strange gray/black color. Is this their natural colors forming or something to do with their sex?
Welcome to the forum Ryanstar.
What kind of fry are you dealing with? In mollies, the base color of fry is quite evident even at birth. In guppies and some other livebearers the base color of the fish comes along later in the process.