Clownfish are among the few species of fish that can avoid the potent poison of a sea anemone. These two species have a symbiotic, mutualistic relationship, each providing a number of benefits to the other. The sea anemone protects the clownfish from predators, and provides food through the scraps left from the anemone's meals and occasional dead anemone tentacles.
In return, the clownfish defends the anemone from its predators and parasites. The anemone also picks up nutrients from the clownfish's excrement, and functions as a safe nest site. The nitrogen excreted from clownfish increases the amount of algae incorporated into the tissue of their hosts, which aids the anemone in tissue growth and regeneration. Marine biologists have theorized that clownfish use their bright coloring to lure small fish to the anemone, which the anemone then kills and consumes.
Another theory is that the activity of the clownfish results in greater water circulation around the sea anemone. Studies on anemones have found that clownfish alter the flow of water around sea anemone tentacles through certain behaviors and movements such as "wedging" and "switching."

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