(Etheostoma fonticola)
The fountain darter (Etheostoma fonticola) is a small freshwater fish found in the headwaters of only two rivers in Texas,United States: the Comal River and the San Marcos River.It is generally smaller than 3 cm (1.2 in) long and feeds on small invertebrates.It is a federally listed endangered species of the United States and is also listed as endangered by the IUCN.