How can I tell the difference between male and female fancy guppies?

I bought 5 fancy male guppies about a week ago, but one of them has developed an very heavy tummy. So heavy that you can see the top portion of his back has a slight hump, not to mention that is seems at times the other fish chase it around more, like they are picking on him... I dont think its possible that I am overfeeding because I only feed twice a day in a pinch a fancy guppy fish food, but does anyone have any suggestions? If it is a female, how long is her gestation period and what do I do once they hatch? Please help; I;d truly appreciate it!!! THANK YOU!

I think that the females are the bland looking ones, with smaller - less pretty tails. Im pretty sure the males are the ones with the long tail fins and nice colours.

Fancy Guppies do not hatch.. They are a live bearer- which means the babies are born alive and swimm within a few minutes. they usually stay on the bottom gravel for a few days...The Male Guppies usually have a more colorful and longer tail than the female Guppie.And They have an extra Fin on the bottom of them That isn't really a fin-just resembles one...Hope this helps you.

Males ALWAYS have a fin called the gonopodium. It looks like this...http://www.aquariumfish.net/images_01/guppy_male_from_heather.jpghttp://www.aqualandpetsplus.com/Livebe6.jpg

the color the males are more colorfull the females are less colorfull

I can use technical words but i prefer to use everyday English---underneath the male you will see wht looks like a small sword or stick-----that is anatomy of a male. Guppies can sometimes change sex but once a female is pregnant, she can give birth up to six months without contact of a male. As for the babies--ask pet store owner for some "anacharis" plants and let some float on top of the water and anchor a small group in the gravel for the babies to hide in--other than that---some babies will be devoured unless you put them in a separate tank--either way take some regular food flakes, smash them up fine and they can digest that. Have fun and enjoy watching the fish! Ps ALL male livebearers have the same anatomy----

males are prettier to look @ so they attract the females. female guppies are plain and bland.

Female do usually have less color and smaller tails. But it is common to accidentlt be given a female with males. Most fish suppliers quickly separate them and many times females do end up with males.The 100% sure way to tell is by it's anal fin. It will be in the shape of a fan for females.http://www.aquariumhobbyist.com/guppies/Femaled.jpgMales have an anal fin that looks more like a stick.http://www.aquariumhobbyist.com/guppies/Maled.jpgGuppies are live bearers which means they birth their babies, they do not lay eggs. So when she gives birth you will see little fish swimming around.If you leave them alone, most of them will prob be eaten. You can choose to either place lots of hiding places and grass in your tank for them to be protected or you can buy a fry net to keep them in it. They sell either nets or plastic floating containers that go into your fish tank but keep the babies away from the adults.I must warn you they have babies ALOT tho, so I don't reccommend trying to save every fry or you'll quickly have too many fish to handle.A female will produce fry on average, once per month, even if a male isn't present in the tank. If the female has been with a male even once, she will have fry for up to 6 months after one mating.

The tail.........

Males have a gonopodium by their analfin, that is a pointylike fin. Females have a fan shaped fin, and are usually more drab colored