The redeye tetra (Moenkhausia sanctaefilomenae), is a species of tetra from the São Francisco, upper Paraná, Paraguay and Uruguay river basins in eastern and central South America. This freshwater fish is commonly kept in aquariums and bred in large numbers at commercial facilities in Eastern Europe and Asia.

It can grow up to 7 cm (2.8 in) in length, and live for approximately 5 years. The red-eye tetra has a bright silver body accented by a white-edged black basal half of the tail and a thin red circle around its eye. It is part of a group that consists of three similar species, the two others being M. forestii (upper Paraguay and upper Paraná basins) and M. oligolepis (Amazon and Paraguay basins, and the Guianas).

Yellow-banded tetra is another common name for the M. sanctaefilomenae. The fish has a yellow band on its caudal peduncle, which differentiates it from the glass tetra.