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The clownfish’s bold, bright marking offer effective camouflage on the coral reefs where it lives; a further defense lies in its special relationship with a sea anemone. The clownfish is never found far from a host anemone on a reef; to stray into open waters would expose this slow swimmer to many predators.

The common clownfish is found among coral reefs in tropical parts of the Indian Ocean and western Pacific Ocean. Because corals are only found in shallow waters where sunlight penetrates, the clownfish is usually found in sheltered areas at depths of 6’ or less, although it is sometimes seen on the outer slopes of reefs at depths greater than 40’. Whatever its location, the clownfish always lives with a host sea anemone. Clownfish are generally known to occupy nine sea anemone species, although each species is usually found with on or two kinds of anemone.

The clownfish’s lifestyle is linked to that of its host sea anemone. Anemones use their tentacles, laden with stinging cells, to trap prey and deter enemies. The clownfish protects itself by secreting a thick mucus all over its skin as a barrier against the anemone’s poison. It also lacks the chemicals that activate the stinging cells. Although the clownfish has many enemies, few predators will pursue a clownfish into the anemone. Away from it’s shelter, however, the slow swimming clownfish is easy prey, it rarely ventures from its host’s protective tentacles.

Because clownfish can not safely venture far from the anemone, they feed mainly on planktonic animals drifting in the current and on certain types of algae growing near the anemone. The clownfish captures prey with close set, flattened teeth and passes it back to the throat. There, strong teeth mounted on gill supporting bones crush the prey into a digestible pulp.

Common clownfish live as a pair in their host anemone, usually with a few juveniles. The breeding pair first cleans a site for the eggs. The female swims slowly over the site, laying 200 to 400 oval, orange eggs, then the male fertilizes them. The fish constantly fan the eggs with their fins and clean them with their mouths. The silvery larvae hatch after sever or eight days, and immediately swim toward the surface. They spend the next seven to ten days as floating plankton, then return to the coral reef when no larger than a human fingernail. They seek a suitable host anemone as soon as they settle on the reef and spend the rest of their lives in that immediate area.

The colorful clownfish is very popular in aquarium displays. Until recently, most aquarium fish were collected from the wild and fishing has depleted fish populations in some areas. Fortunately, popular clownfish species, including the common clownfish, can be bred in captivity for commercial uses. This should let wild populations recover.