Cavefish, Amblyopsidae

Amblyopsidae is a family that holds six species of cavefish, also known as blindfish or swampfish, that reside in swampy and dark waters in eastern areas of the United States. Although there are over 170 species of cavefish, only six of these are classified in the Amblyopsidae family, some of which reside in swamps, while others reside in the water systems of caves like those in the Mammoth Caves in the state of Kentucky. Some of the most notable of these species include Chologaster cornuta, which lives in above ground swamps and Typhlichthys subterraneus, which typically resides in still waters but can also be found in small streams.

Species within the Amblyopsidae family, like all cavefish, have adapted to living in dark areas, with many displaying a lack of functional eyes or a lack of pigmentation. Although they are sometimes called blindfish, many of these species can distinguish between light and dark. They are typically small, reaching a maximum length of 4.3 inches and they have a slender, long body that is often translucent. Their internal body resembles that of a trout or perch, while their external body resembles that of a killifish.

Despite the poor nutrition that cavefish receive in their environment, they experience a safety in the lack of predators and do not have to compete for food with many other fish species. However, the habitats of these species are highly impacted by changes like water pollution and the introduction of exotic species. Cavefish breed only once a year and produce large eggs that are guarded for up to five months. Adults feed on arachnids that fall into the water, shrimp, and gammarus, detecting their food’s movements in vibrations in the water. Four members of this family have been listed as “Threatened” by the World Conservation Union and one has been listed as “Critically Endangered.”

Image Caption: Amblyopsis spelaea. Credit: Eugene van der Pijll/Wikipedia