How do you tell from a fertile goldfish egg infertile egg?

Fertile goldfish eggs are typically clear or translucent, while infertile eggs are usually white or opaque. Fertile eggs will also develop a small black dot, called the eye spot, within a few days of fertilization. Infertile eggs will not develop an eye spot.

Additionally, fertile eggs will adhere to the substrate or aquarium walls, while infertile eggs will often float to the surface.