The Ozark cavefish was listed as a federally threatened species in 1984. It is a small 2-1/4 inch long, blind, pinkish-white fish that lives in caves, sinkholes, and underground springs that are untouched by light in Arkansas, Missouri, and Oklahoma. Due to the dark environment, sight is unnecessary and the cavefish has no eyes. It senses motion given off by organisms in the water to locate food such as plankton, isopods, amphipods, crayfish, salamander larvae, and bat guano. Some threats to the Ozark cavefish include water pollution, declining bat populations (as the cavefish feeds on guano), specimen collection, cave disturbance and destruction, and changing water tables.
Early settlers often found Ozark cavefish swimming in their buckets as they drew water from their wells. They called the fish "spring keepers" or "well keepers," as a sign that the water was safe to drink.