Fish like to eat plants and other organisms depending on their size and habitat. Fish that live in lakes will naturally eat commonly occurring flies that are most numerous in their habitat. Larger fish will eat smaller fish, and bottom feeding fish will eat dead organisms or waste that sinks to the lake's bottoms.
There are over 32,000 species of fish with varying habitats and diets. Pet fish eat flake food or live fish in both freeze-dried or frozen forms. Fish that live in oceans, lake or rivers eat what is available in their natural habitat. Fish have jaws that allow them to eat a diverse diet.