What Do Fish Eat?

When visiting a coral reef the first thing you notice is all the different fish. Not all of these fish live in the same area. Some swim in open water high above the reef top, others move about near the sand bottom; a few can be seen poking about coral heads.

Why are the different fish in different places and what are they doing there? A simple answer is that they are either searching for their favorite food to eat, or they are hiding so they will not get eaten themselves. Fish that eat other animals are known as predators.

Brown Chromis

This group of small chromis hover high above the reef where water movement, called current, carries microscopic animals and plants known as plankton. These tiny bits of life are so small we cannot see them with our eyes, but the chromis can. As the plankton float by, the fish extend their mouths and suck the food in one at a time. Fishwatchers call the fish that feed this way plankton- pickers. Because plankton-pickers feed in the open, they have to be careful not to be eaten themselves. They are quick fish that stay close to the reef for protection. When a big predator fish comes near, they all instantly dart to small holes where they hide until the danger passes.

Graysby

This large grouper just caught a fish that wandered too far from its hiding place.

Scorpionfish

Several fish-eating species do not hunt for a meal. Instead, these fish, known as ambush-predators, lie on the bottom, without moving, and change colors so they are hard to see. When a fish swims too close to this scorpionfish, it will open its great mouth, and instantly swallows the fish whole.

Bar Jacks Hunting Grunts

Another way fish protect themselves from being eaten is to stay close together in large groups, called schools. Fish such as grunts school during the day for protection. When a fish-eating species, such as the fast swimming Bar Jack in the center of the photograph, attacks the school of grunts, the jack has trouble keepin its eye on a single fish. However, if the predator can chase the a fish away from the school, it is easy to grab and eat.

At night, when most fish-eating predators sleep, grunts become predators themselves. They swim out over the sand and hunt for little crabs and shrimp hiding in the sand.

Boxfish

Many other fish also feed in the sand. This boxfish has learned to blow jets of water into the bottom to uncover food.

Spanish Hogfish

This Spanish Hogfish hunts for crabs and other invertebrates in the coral reef's many nooks and crannies. It is happily eating a brittle star that it found under a rock.

Parrotfish Eating Algae

Parrotfish do not eat animals. Instead they eat small plant life, called algae, from rocks. Parrotfish get their name from the hard pointed mouths that looks like a parrot's beak. They use this special mouth as a tool to scrape the plants from the rocks.

predator - one that hunts other animals for food

current - a flowing of water

plankton - floating or weakly swimming animal or plant life, usually very small

ambush - to wait in hiding for the purpose of attack

school - a tightly packed group of fish that move together as a unit

invertebrate - animal without backbone, such as: insects, worms, corals, etc.

© 1999 New World Publications. All rights reserved.