Does the small white spot on the egg yolk indicate that the egg is fertile?
The white spot you are referring to is the germinal disc. A germinal disc, also known as a blastodisc, is on the surface of an egg’s yolk. It is a slight depression on the surface of the egg yolk. Sperm enters through the germinal disc, travel to the center of the yolk, and starts to form a chick embryo.
The only way to tell if an egg is fertile is by incubating it and seeing if the chick is developing by candling the egg. You can candle an egg by shining a strong light. After 7 days of incubation, you should be able to see blood vessels starting to form.