Damselfishes are very common near reefs throughout the Caribbean. They are becoming more common, because of a bad impact people are having on the oceans. Let me explain...

This is a Cocoa Damselfish. Like other Damselfishes, this Cocoa Damselfish eats algae. Algae are small, simple plants that grow on top of the reef. But algae and corals can't live in the same spots on the top of the reef. Remember, corals are animals, and these animals build the reef. So a Damselfish will kill the corals, by biting and pecking at them, to make a dead spot on the coralheads where algae will grow. Then the Damselfish will guard this patch of algae, like a farmer fencing in a field. The Damselfish will chase away other fish, such as Blue Tangs, that might eat their algae.

So, what are people doing that is harming the reef and causing there to be more Damselfishes? Well, people are fishing for Groupers. Groupers are big fish that live near the reefs. Groupers eat Damselfishes, and other small fishes. But people are catching so many Groupers that there aren't many left, and there aren't enough to keep the Damselfishes in check. With no Groupers to eat them, Damselfishes are overpopulating the reefs. The result is that there are too many dead patches of corals, and too much algae. Without the corals, the entire coral-reef ecosystem will be in trouble.

This Cocoa Damselfish was about 4 inches long. Note the yellow color and dusky back. Also note the black spot on the top of its caudal peduncle (where the tail attaches to the body). All of these features help identify this fish. When this fish gets older, it will turn dark all over. This fish was hanging out at the top of a large orange Barrel Sponge.

You can learn more about Corals, Groupers, and overfishing on the ReefNews website. Please visit these ReefNews web pages:
    ReefNews Index to Corals - for more about corals
    Nassau Groupers in your Face - for more about Groupers
    Hemingway and the Reefs of Bimini - for more about Overfishing

ReefNews photographer Jonathan Dowell took this photo using a Canon A2 camera with a 28-105 mm zoom lens in an Ikelite housing. The photo was taken on November 13, 2002.

This picture first appeared on the ReefNews CD-ROM, "San Salvador: Jewel of the New World." Order your own copy of this educational CD-ROM from the ReefNews Online Catalog.

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