Male or female?

[Tuckerp]

This is the largest fish in my tank. It's only about 2 inches long. Wondering if it could be a male? I have a smaller firemouth with more colour on it's belly with rounded fins and a darker brownish body colour... Thought it might be a female?

 

[Tuckerp]

This is the smaller of the two. I thought she was a female but her belly has been getting brighter and brighter (not in this pic...) so maybe she isn't a "her" but a "him"?