Beneath the Surface: The Blindcat Catfish in Danger

In late August of 2023, the U.S. Fish and Wildlife Service proposed listing two extremely rare catfish, the Widemouth and Toothless Blindcats, as endangered species.

They are two of the three known blind catfish to reside in the United States, and both are exclusively found in Texas, specifically 900 feet below San Antonio. These catfish live in caves within the Edwards Aquifer, and as a result of living in this dark and isolated habitat, they have a notably unique appearance. The absence of light means that they don’t need pigment to protect themselves from UV exposure, causing them to appear pink or almost translucent. They don’t have eyes and rely on smell, touch, and taste to find their food. 

The Widemouth Blindcat, or Satan eurystomus (commonly referred to as Satan), lives in the convergence of freshwater and saltwater, referred to as the “bad water zone.” It is 1 to 4.5 inches long and the chief predator of this natural environment. First collected in 1938, the Widemouth Blindcat was a rare sight and has not been seen since 1978.

As implied by its name, the Toothless Blindcat, (Trogloglanis pattersoni) lacks teeth and uses its other senses to search for its meals, which likely include invertebrates and fungus. Originally described in 1919, this catfish ranges from 0.5 to 3.5 inches long, and unlike its widemouth cousin, the Toothless Blindcat has been found as recently as 2013. In 2020, the U.S. Fish and Wildlife Service found DNA evidence that the Toothless Blindcat is still alive. 

These catfish have only been accidentally captured through the wells and water pumps that bring groundwater to the surface, which have been suspected to kill thousands of these fish over time. Their habitat, the Edwards Aquifer, is facing several threats–particularly pollution and excessive water extraction–that may influence the ability for these remarkable catfish to survive. 

As animals of a remote environment, blindcat catfish have likely adapted to live longer and reproduce less, and if their population declines, it could be difficult for that population to grow again. The third blind catfish, the Mexican Blindcat, Prietella phreatophila, is found in Mexico and Texas and has already been listed as an endangered species. 

While the Widemouth Blindcat and Toothless Blindcat are headed towards the same listing, their remote habitat has made population count collection difficult. Since there is limited understanding and data on the two catfish,  U.S. Fish and Wildlife is working to gather population distribution and water chemistry data to further evaluate these threatened fish. Limited knowledge has been a common criticism of the proposed listing of the two catfish, as seen by the public comments to the proposal. We may not be able to enjoy the sight of them as they continue to reside deep underground, but these Blindcats are still valuable animals that deserve our protection.

Thanks to Andrea Laureano and Catelyn Toney for their assistance with this article.