Gerbil Sexing

They are definitely male and female. I have bred gerbils in a 10g before with no problems. The last time I bred gerbils I gave them a wheel. This time I didn't which could account for their large size. I saw the male mating with the female again this week. Maybe something will come of it. I sure hope so.

20 long tank, and 8 gerbils, 4 of each sex. I always have at least one litter in the tank, most of the time 2. I use rodent blocks 90% of the time, and will give them treats every week. Competition is the key. When they have to compete, they seem to breed better. They will pair up, but mating between all of the males to the females happens.
Once I have pair that has given me a couple of litters, I put them in a lab cage, and they usually continue to breed every 6 weeks or so.
they are slow starters, usually take 3 or 4 months for a pair alone after introduction to produce. when I put them together in a colony, they start breeding in 2-3 weeks usually.