If the next task is to work on color,
then after selecting the most suitable male,
it is necessary to find females
that would give the offspring a certain, better color.
For this purpose resort to the test with a hormone.
In 100 ml of 70% methyl or ethyl alcohol 0.1 g of methyltestosterone is dissolved.
The resulting solution is diluted with 900 ml of distilled water.
In the aquarium with selected virgin females,
10 drops of solution are poured into each 19 l of water.
Adding more is dangerous, as this can cause infertility of females.
After 2-6 weeks the females will be colored under the influence of the hormone
and it will be possible to select those
that have the deepest coloring of the desired coloring.
The selected females are placed in the old aquarium water for a month,
and when the coloring almost disappears and the females relax,
they are crossed with the selected males and inbreeding continues.
Of course, this work is very laborious and time-consuming.
Therefore, always start with the best starting material.

Guppy female by Сторожев В.В