Made famous in the movie Finding Nemo, the Clownfish and Clown Anemonefish are one of the reef's most-popular inhabitants. Sadly, it's also a popular aquarium fish. Like most anemonefish, this species lives in a matriarchal group, with the largest member being the dominant female. She is the only female, and she mates with just one of the group, all of which are males. If the breeding male dies, one of the lesser males is promoted to his place. If the dominant female dies, the 'alpha' male changes gender and becomes the dominant female. Then one of the lesser males takes his place.