Godwin, J.R. (1994). Behavioral Aspects of Protandrous Sex Change in the anemonefish Amphiprion melanopus and endocrine correlates. Animal Behaviour 48: 551-567.

Behavioural and endocrine differences between males and females, and during protandrous sex change were characterized in the anemonefish, Amphiprion melanopus. Females are the largest and behaviourally dominant members of social groups, displaying frequent aggression towards their smaller male mates and other smaller non-reproductive individuals. Sex change was stimulated experimentally through females removals in 1989 and 1991. Behavioural samples were taken prior to female removal are from 10 to 45 days after removal in 1989 and 1-20 days after re removal in 1991. Sex-changing individuals showed striking increases in aggression within 1 day following female removal. While the frequency of aggressive acts initiated by sex-changing individuals decreased gradually over the 5-, 10- and 20-day samples, it remained significantly elevated over baseline male levels. A decrease in aggression was also observed from 20 to 45 days after female removal in 1989. Presentations of a model intruder to sex-changing individuals at various stages revealed changes to a pattern of territorial defence characteristic of females. Overall aggression increased and the ratio of attacks at the periphery of the territory to those at the centre increased with time after female removal. There was no convincing evidence of a relationship between plasma levels of the five steroids measured and (1) male/female behavioural differences or (2) behavioural changes with sex change.