Parameters for sexing G. Altifrons?

[stingraybranden]

I would like to give some of my Altifrons for a friend, they are all about four inch currently. I would preferably like to keep a couple of males and females but am not sure how to sex them.

Is it possible at this size an if so what am I looking for? Thanks in advance.

Japes?

 

[Nemesis]

I doubt you will have any success sexing them at that size without a vent.

 

[hbluehunter]

I've been looking for a good thread or site for venting geo's, does anyone have a link for one ?? I have some Altifrons i wanna try and sex also.