Originally Posted by DizzCat
I had a Platy have 5 batches of fry after the male died! Crazy, huh?
Yes, keep that in mind as you will most likely have to cull the batches of fry over time since there will be inbreeding. I had four guppies (2 males and 2 females) explode to about ~20 males, ~9 females and countless (100+) fry. You will either need to find a way to separate the males and females or find a natural predator to keep the population down. For me a large Koi Angelfish made quick work of any fry.
I included a picture, as promised, of the gravid spot on a guppy. It will turn black right before she is about to drop. As said by another poster, the black you are seeing is actually the babies' eyes.