Sexing atromaculatum?

[BigT504]

I have 5 atromaculatum right now that I would like to sex if possible. They are around 4" to 5". Does anyone know what size the atromaculatum have to be before sexing them or any way to distingush a male from a female?

 

[FishingOut]

I may be mistaken but I believe these guys color up like convicts almost. Females get the red belly and yellow/green shines on fins. And males are more yellowish all over.
My buddy bought 2 of these out of a dempsey tank at the LFS because he thought they were a nice looking JD hybrid but turned out to be Cichlasoma atromaculatum. A breeding pair too, and their breeding colors are amazing looking.

 

[Cecropia]

I ran across an old book the other day that mentioned the females having orange "porthole-like" markings under the lateral line. Had a pic of a breeding pair.

Don't know if it means much, just thought I'd throw it out there.