Degus can have different personalities depending on their gender. Females are normally bigger than males, where as males will fight more often when kept together. In order to determine your Degus gender you need to turn it over to see the reproductive organs. This is a difficult task in itself, so a slightly easier way we suggest for the not most tamed of Degus would be to use teasing with a treat to make your Degu stand up against the cage bars for a slightly better view.
Do not be fooled by the cone sticking out where the genitals would normally be, this is only used for urination and not reproduction, a Degu keeps its penis withdrawn and you will only see during grooming or reproduction.
Degu Gender Differences - The Reproductive Organs
The difference between a male Degu and a female Degu is hard to see. The Degu at the top is male and the Degu below the female. When looking at both sexes there is a conical appendage sticking out, this is not a penis, but where the Degu urinates.
As you can see from the picture on the right, the main way to tell the difference is the distance between the sexual organ/ conical appendage and anus. In males, they are around 1cm apart (top picture), where as in females this is much closer at only around 3mm apart (the bottom picture). This can be hard to tell in younger Degus, but with practice you will see the differences easily.