Alabama cavefish

The Alabama cavefish, Speoplatyrhinus poulsoni, is a critically endangered type of cavefish which lives in underground pools in Key Cave, located in northwestern Alabama on the Key Cave National Wildlife Refuge. This is the only known location of the fish, and was discovered in 1974 by Cooper and Kuehne.

Only nine specimens of the cavefish have been observed and scientists estimate that less than 100 of the fish are left on the planet. It is believed that this fish is the rarest of American cavefish and one of the rarest of all freshwater fish. It is the most specialized cavefish known, and exists in the fragile ecosystem based on nutrient rich guano of the gray bat. Researchers have failed to find the fish living in any other location.