Corydoras undulatus is a tropical freshwater fish belonging to the Corydoradinae sub-family of the Callichthyidae family. It originates in inland waters in South America, and is found in the lower Paraná River basin and coastal rivers in southern Brazil and Argentina. It feeds on worms, benthic crustaceans, insects, and plant matter. It lays eggs in dense vegetation and adults do not guard the eggs.