Ozark cavefish

The Ozark cavefish, Amblyopsis rosae, is a small subterranean freshwater fish native to the United States. It has been listed as a threatened species in the United States since 1984; the IUCN lists the species as vulnerable.

The Ozark cavefish is pinkish-white and reaches a maximum length of 2 in (5 cm). The head is flattened, and it has a slightly protruding lower jaw. The fish has no pelvic fin; the dorsal and anal fins are farther back than on most fish. The Ozark cavefish has only rudimentary eyes and no optic nerve. The Ozark cavefish lives only in caves. It has no pigmentation and a loss of unused characters. However, it is well-adapted to a cave environment through well-developed sensory papillae. They feed primarily on microscopic organisms, as well as small crustaceans and salamander larvae. The reproductive rate of Ozark cavefish is relatively low compared to most other fish.

Caves which have populations of the Ozark cavefish all have a relatively large source of nutrients, such as bat guano or blown leaf litter. Water quality in caves that contain cavefish is usually high. Ozark cavefish are able to tolerate the extremely low oxygen content of ground water found in caves. Cavefish tend to occur in flowing cave streams as opposed to quiet pools.

The Ozark cavefish is native to the Springfield Plateau of the Ozark Highlands, southwestern Missouri, northwestern Arkansas, and northeastern Oklahoma. Currently, 15 caves in this area have verified cavefish populations. In Oklahoma, populations are known to occur in Delaware County. There are historical records for Ottawa and Mayes counties. Factors that have led to the decline of the Ozark cavefish include destruction of habitat, collecting of specimens, and disturbance by spelunkers.