"the Kentucky cave-fish"

Examples of blind cave fish from the Mammoth Cave of Kentucky have been known to science since 1841. There are a number of different species that live in the waters of dark limestone caves and as a response to this lightless existence; they no longer have eyes. The fish are small, around 10cm and range in colour from white to light pink. They find their way around the dark tunnels using their other senses and are particularly touch sensitive.  It is listed as Vulnerable to extinction by the IUCN primarily due to its limited habitat range.

Blind Cave-fish, Typhlichthys subterraneus Girard. Mammoth Cave, Kentucky
Public DomainBlind Cave-fish, Typhlichthys subterraneus Girard. Mammoth Cave, Kentucky - Credit: David Starr Jordan, Freshwater and Marine Image Bank, The University of Washington Libraries