The Red Eye Tetra (scientifically known as Bario sanctaefilomenae, formerly Moenkhausia sanctaefilomenae) is a highly popular, hardy freshwater aquarium fish native to South American river basins. Sometimes casually grouped or confused with the similar-looking "Glass Tetra" (Moenkhausia oligolepis), true red eye tetras are easily distinguished by their bright silver bodies, a vivid red semicircle on the upper part of their eye, and a distinct black and white band at the base of the tail. 

They are widely loved by beginners due to their remarkable resilience to shifting water conditions and lower susceptibility to stress-related illnesses.