How can you tell the difference between male and female Guppies?

Although the colors and fins are a good indication of sex, it's not always the case. There are some females that are incredibly fancy. =]

The best indication would be it's anal fin, located near the anus. The male's is pin pointed, while the female's is fanned out.

Here's a diagram:

http://sogua.mamakcorner.com/uploads/Platy_sexing....

The grey ones are probably females. However, in my experience, most young guppies are yellow-ish than grey.

Well the male have big tail fins and are much more colour full than the female. Well the grey ones they prob the female cause not all female guppies are colourful

Male guppies have a gonopodium for reproductive purposes. This is a modified anal fin that looks rod shaped, is held close to the body and points rearward toward the tail. It is used for transfering sperm to the female. As far as being grey it could be a matter of age, but females usually have very bland coloration, so more than likely they are females.

The female Guppies are very neat and tidy and do all the house work. The male Guppies spend all their time down the Mermaid's Arms drinking, telling off colour jokes and farting a lot. I hope this helps.

male guppies have big fancy tails and are very colourful, female guppies are duller in colour are have smaller tails they generally look grey, also no that they reproduce like crazy so watch out you should also always have at least 2 females to every male that you have because the males will chase them around so much they can die from stress

Male guppies are nice, bold and colourful, this is because they need to atract females, which they do a lot, so be warned, the females are greyish because they dont need the colour, however, they may have a colourful tail, but it is smaller. she will also have a dark black mark near her tail, where the tail starts. but yes, young guppies are grey.

anyway, Merry Christmas ^_^

The males have a smaller body and have a more colorful and longer tail. Usually.

The females are not as colorful, and have a larger body. Tail is usually short and lacking in most color.

They are probably the easiest fish to sex.

male guppies have long beautiful tails and bright colours while female guppies are dull in colour and are larger than males

the males have the beautiful colorful tails. the females are plain

males - longer tail fin