Reef Fish

Reef Fish

Global Changes, Local Effects

Reef Fish

Story Behind the Science

As their name suggests, reef fish make their homes in coral reefs. Reefs are known for their great biodiversity, as one-fourth of all marine life rely on them for food or shelter at some point during their lifetime. Unfortunately, due to human and natural threats, some reef habitats have been damaged if not completely destroyed.

Reef fish play an important role in coral reef ecosystems. Some of them eat seaweed, which grows faster than coral. Seaweed is a competitor that could easily smother reefs if they weren’t controlled by the fish that consume them. Other reef fish prey on animals that are destructive to reef growth, including some other fish, sea stars, worms and snails.
Reef Fish


Reef fish depend on the reefs they live amongst for survival, so what has a negative impact on coral reefs also has a negative effect on the fish and other animals that live there. Two devastating natural threats to reefs include coral bleaching and the Crown of Thorns sea star, a destructive reef dweller.

The vibrant colors of corals are a result of the algae that live within them. When algae die, corals lose their color. This is the main effect of coral bleaching, which occurs when water temperatures within a reef habitat become warmer. Coral bleaching reduces skeleton growth and reproductive abilities and can potentially cause the death of an entire coral colony if conditions are severe enough. When algae from corals are depleted, reef fish that feed on the algae are also affected by the loss of a major food source.

Another threat is an inhabitant of coral reefs: the Crown of Thorns sea star. Although these reef dwellers are naturally found in reef ecosystems, they can have a devastating effect if their population is too large within a single area. The Crown of Thorns consumes coral tissue, literally sucking the life out of the corals it feeds upon.

Reef Fish

Fast Facts

Did You Know?

  • Coral reefs cover a total of less than two percent of the ocean and not even one percent of the whole Earth.Learn More »
  • According to the Census of Marine Life, there are more than 230,000 species of animals that can be found in the world’s oceans.Learn More »
  • Many reef fish have adapted to the coral reef environment through changes in their body shape, color and feeding strategies.Learn More »
  • Coral is valuable in medical research because it may contain compounds that can treat diseases such as cancer, diabetes, AIDS and heart disease among others.Learn More »
  • Coral can be described as an animal, a vegetable AND a mineral.Learn More »
Compare & Contrast Reef Fish Marine Fish
How many species? 4,000 16,700
Where do they occur? Reef fish can be found in both deep- and shallow-water reefs, though they are most common in shallow tropical waters. Marine fish are found in all of the world’s oceans.
What do they eat? Some reef fish eat other smaller fish or crustaceans, while others eat algae, seaweed or plankton from the reefs themselves. Some fish actually eat dead coral and rocks within the reef ecosystem. Depending on their size, marine fish can eat smaller fish, plankton, algae or coral.
Do they have predators? Larger fish and octopuses are a couple predators of reef fish. Other predators include animals that are destructive to the reefs that are their homes (for example, the Crown of Thorns sea star). Sharks, barracudas, rays, dolphins, whales and other larger marine animals

BBC Worldwide, "Coral Reef Fish Danger -- Blue Planet"

Reef Fish

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Conservation Organizations for Reef Fish & Coral Reefs