The clown fish form a symbiotic relationship with sea anemones and small groups of these fish are found with the sea anemone. The sea anemone is highly toxic and few other fish can survive its poison. It is believed that the co-evolution of the two species has made the clown fish immune to the sea anemone.

The clown fish feeds on the undigested matter of the sea anemone and helps to keep the water clean. The movement of the clown fish improves the water circulation around the sea anemone. The clown fish is also protected from other predatory fish by the poison of the sea anemone.