how to tell genders in guppies

Question
Dear Richard,

I just got some new guppies from the pet store. I had one which I believed was male, so I asked for females, and the store owner showed me some brightly coloured fish. This struck me as odd, because I'd thought that only male guppies were coloured, so I asked, and the store owner told me that guppies' genders could be determined by the tail.

How do you tell the difference between a male and female guppy?

Thanks for the help.

Answer
Hi Jascha

While it is true that female Guppies usually are not as colorful and have shorter finnage, this is not always the case. The easiest way to sex Guppies as with any livebearer, is by the anal fin (underneath closest to the tail) In a male it is tube shaped, in a female it is fan shaped.

Hope this helps, good luck!

Richard