Creating a new strain working with related genes
requires using *line breeding
or IN*breeding methods (preferably a bit of both.)
Bringing two unrelated strains together
would be INTER*breeding.
This would bring separate and granted
possibly unknown genetic factors together.
Casual guppy breeding using either method
could result in poor quality fry.
However, we’re not talking about someone
who bought a pregnant female guppy
just too see what would happen.
Responsible crossing of different genetics
is the only way to ultimately create
any new strain (natural mutations excepted).
Once the (e.g Albino & Gray) genes are mingled,
the option to breed parent to offspring
or sibling to sibling (inbreeding)
can strengthen desired qualities.
You can also purchase genetically distinctive fish
and line breed – essentially crossing back and forth
between two or more established strains
to achieve the same desired traits.
No matter how you breed guppies,
‘fresh’ genetics have to be injected
down the line at some point,
or the guppies would become so inbred
they would end up in poor quality and bad health anyway.