The sex themselves bang.. (Yeah, I said it that way just for your benefit..

)
Seriously though, whichever fish is the dominant will become the female with typically up to 3 subordinate males in the group. - If something happens with the dominant (female) the highest ranking male then becomes female..
So, for instance.. - With the movie Nemo... - I had a great time teasing my kids in saying that Nemo's dad had a sex change after he lost his mom..
But... - Bang, your question is still a good question.. - I mean, if it's not old enough to be sexually mature it wouldn't be either yet..
My guess though is that if everything else is fine with it. - Its eating good, water quality is good and its just acting "wierd" and spending a lot of time "hiding" that its actually trying to spawn.. - Just that there's no male so if it does, the eggs will
probably not be fertilzed. - I say
probably because some wierd "stuff" happens in nature sometimes and well, who knows.... :wink: