The reddish tuco-tuco (Ctenomys frater) is a species of rodent in the family Ctenomyidae. Five subspecies have been recognized, some formerly designated as separate species. It is found in Argentina and Bolivia at altitudes from . This tuco-tuco is fossorial, like others in its genus. Its diet consists of underground tubers and roots. Its karyotype has 2n = 52 and FN = 78.

It lives in colonies in areas with suitably soft, dry soil. Both undisturbed and disturbed areas provide suitable habitat. Its conservation status is assessed as "Least Concern" by the IUCN.

Taxonomic history: Budin´s tuco-tuco (C. budini) was formerly considered a distinct species, endemic to southeast Jujuy Province in northwest Argentina, suspected to be threatened. The IUCN and ASM currently view it as a subspecies of C. frater. It was named after Emilio Budin, an Argentine specimen collector who worked with Oldfield Thomas.

The forest tuco-tuco (C. sylvanus) was formerly considered a distinct species, endemic to Salta and southeast Jujuy Provinces in northwest Argentina. The IUCN currently recognizes it as a subspecies of C. frater.