these are Metynnis but it looks like there might be more than one species on there. Maybe maculatus and hypsauchen?
gentle lemur posted while I was deliberating.I will agree with him for rubripinnis for most of them (not maculatus as I posted), but I still think there's a hypsauchen in the middle as well.
Thanks Chlidonias and gentle lemur and I had also the impression that there were several similar looking species together.
