I have recently bought 10 male fancy guppies for my 63 litre tank. I have bred guppies a few years ago, so i had some knowledge of the breed. However, about 4 hours after i introduced them to the tank, i noticed that many of them were chasing one guppy, who although came from the same tank as them in the store and was sold as a male, it is bigger than the others and has a more female-like shape. It looked like the others were trying to mate with her, but i cannot be sure, it might just be an older, fatter guppy. I cannot tell if he/she has a gravid spot as he/she has a half black body. Can someone help? thanks 
