Are you looking for the actual Geophagus genus? Or close related genus?
Smaller Geophagus species would include: G. parnaibae, sp. pindare, sp. Tapajos 1, sp. Tapajos 2, sp. Araguaia and G. taeniopareius.
Closely related genus would include: the redhump geo species, Satanoperca pappaterra, Guianacara genus, Biotodoma genus, Microgeophagus genus, and Apistogramma genus. There are a few others, but most are hard to find.