Hays County is home to more than fifty species of freshwater fish. Many are fairly common and quite abundant, including a number of sportfish species. However, several species are less far-reaching and are unique to central Texas. The state fish of Texas, the Guadalupe Bass makes it’s home here. The Fountain Darter, listed as federally endangered, is found nowhere else in the world other than in the San Marcos River and the nearby Comal Rive, named after the county it runs through. This fish, as well as a number of crustaceans, salamanders, and invertebrates are endemic to central Texas springs and aquifers.
The clear waters of Hays County treat snorkelers to a rich and diverse assemblage of minnow, sucker, catfish, sunfish, gar, and darter species. Freshwater Eel and Big Claw River Shrimp (which can exceed two feet in length) fulfill part of their complex life cycles in the County’s waters, as well. Though not as naturally rich in mussel species as other areas of the country, Hays County does harbor several species including two with protected status, the Texas Pimpleback and the Golden Orb.
Not all the fish and mussel species found in the Hays County came here naturally. Several have been introduced intentionally, mostly for sportfish purposes, with mixed results for the environment. The introduction of Redbreast Sunfish, for example, had minimal to no negative impact to the aquatic environment, while the introduction of the Smallmouth Bass had deleterious consequences on the native Guadalupe Bass. Other species that have established themselves in the waterways of the County due to accidental or negligent releases include a variety of catfish species used for aquarium algae control (generally referred to as plecostomus) and a number of snail and mussel species, some of which are also associated with the aquarium trade.