Hill Country streams are home to a variety of native Texas fish, including the state fish of Texas, the Guadalupe bass, which is found nowhere else. Most of these streams are small, shallow creeks or rivers populated with sunfish, channel and flathead catfish and various species of gambusia. Examples of gambusia can be seen in the small aquaria in this area.
While Hill Country streams have fast-flowing sections with rapids, they also have quiet pools where catfish and largemouth bass live. Since these streams flow over limestone, a very porous rock, their water sometimes disappears below ground then reappears farther downstream. Where streams flow over fractured bedrock, they recharge the underground reservoirs called aquifers. Many Texans depend on these aquifers for their water supply.