Lamarck male/female

[cccapt]

I have a female (I believe) Lamarck about 5" that been in my tank for about 2 yrs now. I would like to add a male, if I can find 1, but I'm not sure how to tell them apart. Does anyone have a pair, or at least a male so I can see the difference between them? Do you think I'll have any luck pairing them?

Here's the female 1 yr ago.

And today.

 

[rachenbrazil]

Better to add smaller female to make your current fish turn into male . Never seen males for sale.