Is there a way to tell the difference between male and female PJ Cardinals?

[seeinstars89]

I wanted to get my Pajama Cardinal fish "Flusher" a girlfriend but I dont know if Flusher is a male or female... He is huge, about 3". If I got another one and it was the same --- would they fight? I have never seen a cardinal as large as mine is so anything I would get would be alot smaller? Will they change --- like a clown? Or should I just not risk a fight by not getting another one at all? Here are some pictures of him....

I have heard different things from people about if you can tell by looking at them... Anyone have any ideas?

 

[dreamweaver]

Apparently there is no sure fire way to determine the --- of PJ Cardinals... Online googling only produced the fact that it is very hard to distinguish... Some say the male has a longer secondary dorsal fin and/or larger mouth.. Some give the description of the female as having a "somewhat" (whatever that means!) more rounded body.... But nowhere did I find these statements given as actual facts. I suppose that is why several sites suggest buying three for breeding purposes...
As far as compatability with one another - all sites that I've seen say that these are peaceful fish that get along with their own species and other fish, but of course size differential was not mentioned... My PJ looks to be about the same size as yours and hasn't bothered any of the smaller inhabitants of my tank - but then again I only have the one...
I do wonder what kind of problems you might face should you do obtain a male and female... From what I've read, PJs become very aggressive during the spawning period - with the males carrying the eggs in their mouth while the females defend from any perception of threat - and this goes on for about a month... (a fact that I find amazing since the male doesn't eat while carrying the eggs! You would think he'd starve to death!) ... Something to think about....