How to identify guppy fries' sex

[phuakokhong]

Got 9 guppy fries from an albino full red, they are now about 6 weeks old. Understand that I have to separate male from female as soon as i can to avoid any premature mating. however, at now 6 weeks old, i still unable to clearly see the gonopodium. the colour of the tail are showing now, but bodies are yet to show colour yet, which at one look, looks like all female to me. how soon will the colour of the body appear if it's a male?

thank you.

[Shrimpong]

How big are they now? By 1cm should be able to see the botttom.

[phuakokhong]

How big are they now? By 1cm should be able to see the botttom.

Now they are 2 months old, i managed to identify the sex from the development of the tail last week. My eye sight not so well to see the gonopodium when they are 1 cm long!