I would say youve got yourself a male demp there a well fed and stress free male from the looks of it I say male because of the lack of blue coloration under the gill plate the profile is a bit misleading but fins appear to indicate male as well the only female trait i would say is the more rounded body shape males are usually longer more streamline and lack the "hump" leading up to the dorsal finthis is my young male for comparison
This is both male and Fem the lower one is my Fem for comparison the blue "beard" is the best indicator of a female dempsey which your dempsey lack another feature that suggests male