Corydoras pygmaeus, or the pygmy corydoras or pygmy catfish is a tropical and freshwater fish belonging to the subfamily Corydoradinae of the family Callichthyidae. It originates in tropical inland waters in South America, and is found in the Madeira River basin in Brazil.

Corydoras is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almost equals the area of distribution of the family, except for Panama where Corydoras is not present. Corydoras species are distributed in South America where they can be found from the east of the Andes to the Atlantic coast, from Trinidad to the Río de la Plata drainage in northern Argentina. Species assigned to Corydoras display a broad diversity of body shapes and coloration. Corydoras are small fish, ranging from 2.5 to 12 cm in SL., and are protected from predators by their body armor and by their sharp, typically venomous spines.