Black and white Clown Fish are a striking colour variant of the common Clown Fish (Amphiprion ocella

Black and white Clown Fish are a striking colour variant of the common Clown Fish (Amphiprion ocellatus). This species is known for its protoandrous hermaphroditism, which is a type of sequential sex change. Groups that live together consist of two large fish, the breeding male and female, and several other smaller fish. If the female is predated or removed, the breeding male will transform into a female, and one of the smaller fish will rapidly grow to be the sexually mature male of the group. 

Photo: anonymous