In clownfish, which sex change commonly occurs when the dominant female dies?

In clownfish, the common sex change after the dominant female dies is male to female.

Clownfish live in social groups within sea-anemone hosts. The largest individual is normally the breeding female, while the next-largest is the breeding male. Smaller fish remain reproductively immature and form a strict size hierarchy.

If the breeding female disappears, the breeding male changes sex and becomes the new female. The largest remaining immature fish then moves up the hierarchy and becomes the breeding male. This process is called sequential hermaphroditism, specifically protandry because an individual functions first as a male and later as a female.

The change is controlled by social conditions and involves behavioral, hormonal and anatomical transformations. Clownfish are not born permanently assigned to one reproductive sex in the way many mammals are. The direction is also easy to reverse: in some species, if the female disappears, the male changes; removing the dominant male does not normally cause the female to become male.