I'm trying to find out the genders of my 1st batch of guppy fry, but it's been one of the hardest things fish-wise that I've ever attempted. They are about 6 weeks old now, and I've read that by 8 weeks the females and males should be seperated to avoid imbreeding. I think I can see slight gravid spots on a few, but they are light colored so it's very hard to tell. There are 8 in this batch, is it possible they're all girls? If I look at their fins, they all have the female look there. Any advice?