Agree
the males have a much steeper profile, and usually longer fin trailers.
Here are some examples of male/female differences in Geophagines.
These traits are fairly universal throughout the Geophagine tribe, so my examples are not specifically "red head Tapajos,".
Female Gymnogeophagus quilero Above, male below
Above male foreground, female further back, of Gymnogeophagus sp Paso Pache.
Below a male of the altifrons group (same group as your Tapajos)