I agree with FF
I have spawned 201/102 many times and still I am never sure on sexing them
For me they are a fish that spawn best in a group I have 7 and I am still not sure of the sex of most of them but I get 20 to 30 fry every 6 to 8 weeks of them
They are from 5 cm to 7.5 cm long. I bought them 18 months ago (they must be at least two years old), but growth rate is terribly slow. I guess that separate tank will do.