Sex change from male to female: active feminization of the brain, behavior and gonads in anemonefish

12 pages, 5 figures.-- Open accessIn the majority of vertebrates, including fishes, sex is determined during early development and remains unchanged throughout life. Nonetheless, a small number of teleosts have the capacity to change functional sex in adulthood, exhibiting environmental sex determination. This unique sexual strategy is called sequential hermaphroditism and occurs sporadically among fish. It has been described in462 species from 41 families and 17 orders, accounting forabout 1.5% of teleosts (Nelson et al. 2016; Kuwamura et al. 2020). The majority of these species occur in the marinerealm, especially on coral reefs, as only 2% of fish with the capacity to change sex inhabit freshwaters (Pandian 2010; Kuwamura et al. 2020). Three different forms of sex change have been described among sequentially hermaphroditic fishes: protandrous (fish mature first as males and then change to females), rotogynous (fish mature first as females and then change to males), and bidirectional (fish can change back and forth between male and female phases). The most common type of sequential hermaphroditism in teleosts is protogyny (female first) with a prevalence five times higher than the two other strategies (Kuwamura et al. 2020)N