Breeding small strain of guppies

I want to breed a strain of small guppies.

I chose a couple pairs of guppies born and grow up in small aquariums (about 1,5 liters).

This pair was born in July 2016 and grew up in this aquarium.

I choose fish of the smallest size among fish of the same brood.
This pair is about 6 months old.
Here you can see the male performs what seems to be a mating dance.

And here is another couple.

Let's take a closer look at them.

It is a female.

Here comes her male.
This couple is about 5 months old. They were also born and grown in a small size aquarium.
All fish are about 2 cm long.

There is a possibility that living in small size aquariums may stall growth of the fish.
 It is desirable for breeding a small size strain.

I will keep you updated about this project!
Have fun and happy fish :)