Fountain Darter

The fountain darter (Etheostoma fonticola) is a small freshwater fish found in the headwaters of only two rivers in Texas: the Comal River and the San Marcos River. It is generally smaller than 3 cm long and feeds on small invertebrates. It is a federally listed endangered species of the United States.These fish have also been sighted in the Guadalupe River in 3 different places.

They live in the vegetation at the bottom of clean springwater rivers, the overuse of such springs being the main reason for their depletion. An extra worry for the future of fountain darters is the parasitic, non-native trematode (Centrocestus formosanus), whose impact on the darter population is not yet known. As of 2004 only the Comal population is seriously affected by the parasite. The National Fish Hatchery & Technology Center in San Marcos keeps a reserve population of 500 adults as a hedge against a man-made or natural event wiping out the fish in the wild.