Why can overfishing lead to ecosystem collapse?

Ecosystems are complex and have many components to them. When people hear the word ecosystem, we mainly think food chain. Considering this we will put it in this context. In a food chain, we have predators and preys. Predators are at the top eating prey. If you take anyone of these components out the ecosystem will collapse.

Humans are predators. Overfishing is taking out too much prey from the ecosystem. If we take too many fish out of the ocean we will destroy everything. For example, if we take out a fish that usually eats a certain type of plant and that fish is the only eats that plant. If there is nothing to kill that plant then that plant will start growing more and maybe taking over other territories. This will kill other plants. Then another fish that only eats that plant will die. Then bigger fish that ate that fish will die. It will start a chain reaction.

This is a hypothetical situation and there are many different factors to consider as well.