When a sea anemone is not available in an aquarium, the clownfish may settle in some varieties of soft corals, or large polyp stony corals.[citation needed] Once an anemone or coral has been adopted, the clownfish will defend it. As there is less pressure to forage for food in an aquarium, it is common for clownfish to remain within 2-4 inches of their host for their entire lifetime.[citation needed] Clownfish, however, are not obligately tied to hosts, and can survive alone in captivity