I'm a Gymnogeophagus fan, although they wouldn't go with rays unless they were the Uruguayan cool water type.
Gymnogeophagus quilero (yerbalito)
Gymnogeophagus sp Paso Pache
that is Acarichthys heckelii (Threadfin Acara). They are my favorite geo and the kind that got me into geophagus in the first place. Something about their vibrant red trailers that grow off all their rear fins is just tranquil. Amazing to watch these guys develop.