Widemouth blindcat (Satan eurystomus)

Widemouth blindcat specimen
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Widemouth blindcat fact file

Widemouth blindcat description

GenusSatan (1)

A bizarre looking fish, the appearance of the widemouth blindcat reflects the unique habitat it occupies. Living in dark, underground waters, the widemouth blindcat lacks eyes and its smooth, scaleless skin possesses no dark pigments and so appears white or pink in colour (3) (4). The head and snout are broad and flat (3), with long, whisker-like barbels (fleshy projections) around the mouth (4). It has a long, high adipose fin on the back, and a strong spine in front of the dorsal and pectoral fins (4). It occupies the same underground pools as the toothless blindcat, but can be easily distinguished by its well developed jaw teeth (3).

Length: 13.7 cm (2)

Widemouth blindcat biology

Due to the inaccessibility of its habitat, little is known about the widemouth blindcat. It is known to eat shrimp, amphipods, and isopods, and may also prey on the toothless blindcat, Trogloglanis pattersoni (5). The widemouth blindcat possesses a well-developed lateral line (a row of receptors that can detect movement via vibrations in water), which is thought to be the primary sense with which it locates prey (6). It is this, along with the frequent presence of crustacean skeletons in its gut, and its muscular stomach, that suggests that the widemouth blindcat may be the top carnivore in the Edwards Aquifer system (6).


Widemouth blindcat range

Occurs only in the San Antonio Pool of the Edwards Aquifer, in and near San Antonio in Bexar County, Texas (3).


Widemouth blindcat habitat

The widemouth blindcat is a subterranean freshwater fish, inhabiting underground pools at depths of 305 to 582 meters (5).


Widemouth blindcat status

Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).

IUCN Red List species status – Vulnerable


Widemouth blindcat threats

As the widemouth blindcat occurs only in one underground pool, any change in the pool environment could rapidly impact the entire population, making this species very vulnerable to extinction. The widemouth blindcat inhabits water that is removed for human use (7), particularly for the enormous city of San Antonio. As San Antonio continues to grow at a rapid rate, ground water extraction has an increasing impact on the blindcat’s habitat (8). In addition, as human populations rise, so does the probability of contamination of the Edwards Aquifer from agricultural and industrial runoff, such as fertilisers, pesticides and heavy metals (5) (7).


Widemouth blindcat conservation

In addition to the IUCN classifying the widemouth blindcat as Vulnerable (1), the Texas Parks and Wildlife Department consider this species to be Threatened (9). Controls are placed on water extraction from the Edwards Aquifer by federal and state authorities, offering the toothless blindcat a little protection (8). However, to fully protect this little-known species and the unique aquatic ecosystem it inhabits, further studies and long-term monitoring are required to inform conservation actions (8).

View information on this species at the UNEP World Conservation Monitoring Centre.


This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk


Adipose fin
In some fish, a second dorsal fin consisting of a flap of fatty tissue, which lacks supporting rays.
A group of small shrimp-like crustaceans that includes sandhoppers, beach hoppers, and water lice.
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
The dorsal fin is the unpaired fin found on the back of the body of fish.
A diverse group of crustaceans, with flattened, segmented bodies, that includes pill bugs and woodlice.
Pectoral fins
In fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.
Living underground, in caves or groundwater.


  1. IUCN Red List (September, 2007)
  2. Page, L.M. and Burr, B.M. (1991) A Field Guide to Freshwater Fishes of North America North of Mexico. Houghton Mifflin Company, Boston.
  3. Florida Museum of Natural History (March, 2008)
  4. Wheeler, A. (1985) The World Encyclopedia of Fishes. Macdonald and Co. Ltd., London.
  5. NatureServe (March, 2008)
  6. Langecker, T.G. and Longley, G. (1993) Morphological adaptations of the Texas blind catfishes Trogloglanis pattersoni and Satan eurystomus (Siluriformes: Ictaluridae) to their underground environment. Copeia, 1993(4): 976 - 986.
  7. Proudlove, G.S. (2001) The conservation status of hypogean fishes. Environmental Biology of Fishes, 62: 201 - 213.
  8. Texas Natural History Collections. (2007) Trogloglanis pattersoni. Texas Natural Science Center, The University of Texas at Austin.
  9. Texas Parks and Wildlife (September, 2007)

Image credit

Widemouth blindcat specimen  
Widemouth blindcat specimen

© Manuel Lemus / Texas Natural Science Center

Manuel Lemus
c/o Jessica Rosales


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