Well I googled Rio Ventuari and from what I could tell from a bad map, the river is in Venezuela. Then I looked on the catalogue of geophagus here on CRC and it said only abalios, dicrozoster, gottwaldi, grammepareius, and taeniopareius are found in Venezuela. Dicrozoster and taeniopareius can be eliminated due to pre-opicular bar. Sadly grammepareius doesn't have any available photos or descriptions. Gottwaldi only has a drawing of it, but it does say it has a infraorbital strip, but not quite sure what that means. It could be an abalios however the caudal pattern is messing me up. Abalios has a striped caudal pattern, correct? And the one in the second photos looks to have a spotted one. Well I hope this helps some!