Sexing
The difference between a male and a female fat-tailed gerbil is the same as with other small rodents. This difference can be seen at the distance between the urinary and anal openings. The distance between these openings in male fat-tailed gerbils is much larger than it is in females. Adult males have a large bulge at the base of the tail that is their scrotum. So their testicles are clearly visible. This is totally absent from females. When the pups have an age of about 2 weeks the hairs on the belly start to grow and bald spots can be seen on the belly of the females. These are her nipples. These bald spots are absent in males.
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