Here's why:

* Fish: Many fish species lay thousands, even millions of eggs at a time. This is because a large number of eggs are needed to ensure survival as many eggs are eaten by predators or don't survive.

* Frogs: While frogs lay eggs, they typically lay a few hundred at a time, sometimes in clusters called "frogspawn."

* Spiders: Spiders don't lay eggs in the traditional sense. They create egg sacs that contain many eggs, but the number varies depending on the species.

So, while all three animals reproduce by laying eggs, fish lay the largest quantity by far.