The caudal fin is what screws it up for me. G. abalios' caudal fin has a mix of spots and stripes while your photos only show spots. Also G. altifrons has a tiny lateral spot of 4 scales or smaller.
Right now I'm leaning towards Geophagus sp. Tapajos II. These are a different fish from G. sp. Red head Tapajos. I don't have much info on them but that is what your fish remind me of. I'm definitely not positive on the ID but maybe try posting on MFK, there are more Geo enthusiast over there that are good at IDing them.