The shiny guinea pig (Cavia fulgida) is a guinea pig species of southeastern South America.
The rodent is endemic to Brazil. It is native to the Atlantic Forest ecoregions.
Wagler first called the species Cavia fulgida in 1831; P. W. Lund identified a Cavia rufescens in 1841, but since Oldfield Thomas (1901) these are considered to be identical species.