Clownfish, also called anemonefish, live in the warm waters of the Pacific and Indian Oceans, the Red Sea and the Great Barrier Reef. These fish have a symbiotic relationship with anemones, which are slow-moving invertebrate animals that look like flowering plants. Clownfish never venture far from their anemone partners.
Clownfish are immune to the poisonous tentacles of sea anemones. The fish can therefore swim and wallow among the tentacles, where they are protected from predators and food is abundant. In addition to the algae, krill and plankton in the water, clownfish feed on debris from the anemone's meals.
It is theorized that clownfish may assist anemones by luring prey into their tentacles. Anemones also receive nutrients from clownfish waste. Nitrogen in the waste aids anemone tissue growth and regeneration. In addition to this, the movements of clownfish help circulate water around the Anemone.
Clownfish are born male and change into females at maturity. They live in colonies consisting of a dominant female, an adult male, and several juvenile males. If the dominant female dies, one of the juvenile males undergoes a period of rapid growth, which causes it to change into a female. The males care for the colony's eggs until they hatch.
Clownfish are named for their orange-, white- and black-striped patterns, which are reminiscent of a circus clown's costume. There are 28 species of clownfish, with many color and pattern variations. Clownfish are bred in captivity for the aquarium trade, as they are popular saltwater aquarium fish.