Yup, It could be C. kelberi too.
I have C. kelberi similar to yours at that size.
3 prominent bars, red eye, but mine, shows yellowish-green shine little bit on it (between bars), maybe because different water parameter, but your guys could be C. kelberi too.
Just wait until 10'', then it will unmistakable, those guys grow really fast anyway.
So my conclusion (based on red eye appearance), that could be C. ocellaris from Guyana, C. monoculus form Nanay River system, or C. kelberi from Bahia.
But I inclined to say C. ocellaris, only time will tell the truth anyway.