Why are there so many fish in the ocean?

The ocean is very large and contains a wide variety of habitats that can support different types of fish. Some areas of the ocean, such as the Grand Banks, are especially rich in fish because of the abundance of plankton and other food sources. Plankton are small organisms that drift in the ocean and are an important part of the food chain for fish. Fish also reproduce very quickly, which helps to keep their populations stable.