I’ve always seen Initial as being the same as Terminal just two different names.
Transitional is the middle between Terminal/Initial Male and Female.
This really got me wondering because I thought I had read there was a difference a while back but I couldn’t remember where. So, looking up the difference again, here’s what I found:
This one basically states that initial phase males are males that look like and behave like females, but are actually males and will attempt to essentially indirectly breed.
This one’s “Population Ecology” section says the following; “Removal of terminal phase males temporarily disturbs the male to female equilibrium within the population. Initial phase males and females alter their physical colour, latter is colour and sex, in order to become terminal males to balance the male to female ratio. Initial phase females display terminal male behaviour within minutes; bodily colours are changed in a day, becoming distinctly visual in four days and swift transition from ovaries to testes, producing functional, mature sperm in less than eight days (Warner and Swearer, 1991).”
Last one:
www.sciencedirect.com
The quote from here - “Terminal-phase individuals (supermales) arise from either irreversible sex change in a female, or irreversible morph change in an initial-phase male (Figure 1(b)). In addition to the striking color dimorphisms, there are dramatic differences in body size, reproductive behavior, and fecundity (e.g., Petersen et al., 1992; Warner and Schultz, 1992).”
So, there is a difference between Initial Phase Male (apparently also known occasionally as “sneaker males” because they retain the juvenile/female coloration and behavior while trying to “sneak in” mating) and Terminal Phase Male (supermales), but I’m not entirely sure how Initial Phase Males occur (i.e. I’m not sure if they’re born male or if they started transitioning from female to male then stopped - I’ll have to do more research on this).
Either way, maybe a better way to phrase what I was getting at earlier would be - female wrasse transitioning to male can stop/reverse the process as long as it hasn’t gone too far, as was demonstrated by my initial article (I’m not entirely sure when they can no longer reverse it, it might be like 50% transitioned, 20%, 90%, IDK).
Edit: just adding for the OP, the terminal male thing above means that if you wrasse is showing male coloration, it is - irreversibly - male. As I can’t think stated above, though, stress can cause discoloration for you fish (and behavior changes too).
