The Silver Dollar Piranha (Metynnis Argenteus) clearly seems piranha-ish but not the same family as the red belly piranha, or any of the Serrasalmus, thats prolly why the latin name mentions a different family, namely Metynnis, its silvery color explains the Argenteus (Silver) but im still confused why its rare red stripe or line has not been taken into account when naming it, cause it is so striking for correct identification. Very beautiful fish, if you manage to not fall asleep watching it. Maybe its discoverer did just that ha