Without light guppies (and most other species of fish) can not see one another so it would be extremely difficult for them to locate one another let alone breed successfully. Therefor I would say that the effect of light would be to 'enable' reproduction of guppies.
Guppies typically shouldn't react to lights unless they are extremely bright and should not be used.
For all the info you could possibly desire on Guppies check out this link.:-http://www.practicalfishkeeping.co.uk/pfk/pages/show_article.php?article_id=492
Dissolved gasses, light intensity, pH level, and water availibility.
No, any effect
response
Some herbalists suggest that yellow chrysanthemum tea can effect human reproduction. It has calcium and iron, as well as vitamins A, B12, and C.
If the water temperature does not get too cold, and the water continues to be aerated, then the darkness won't matter. Guppies survive perfectly well in the dark.
Chester Carlson invented the electrostatic dry-copying process of duplication that became known as xerography. This process used the effect of light on photoconductivity
Guppies are surface fish and they also enjoy swimming/playing in water currents that is why they are there.
any color that is light or black with another bright florensent color.
Good nutrition
Fries (the term for baby guppies), are eaten by older guppies, but guppies are eaten by fish like tuna.
What are guppies