This has nothing to do with finding Nemo. This is in fact real, and is something that really happens with clown fish. If the female of the school is dead, gone, or no longer found in the school, the high leader male will take the place of the female by actually becoming a female clownfish, and letting the lower rank male become a rank higher and thus mates with the new female for survival. It's a real gender bender ^^
Hey guys there is a new version of the カクレクマノミ物語 story in dlsite maybe someone should buy that and add it to the ehentai gallery :http://www.dlsite.com/maniax/work/=/product_id/RJ152835.html