The Devils Hole Pupfish is an endangered fish species native to the desert of Nevada. Pupfish in general tend to be desert fishes, adapting to live in extreme environments across the American Southwest and Mexico, but the Devils Hole Pupfish is a particularly remarkable example of this group of fishes. These fish have adapted to live in the 92 degree Fahrenheit (33 degrees Celsius) waters of Devils Hole, a geothermal pool in the Amargosa Desert.
If you’re wondering about the obvious grammatical issue with the name “Devils Hole,” you can thank the United States Government. Devils Hole was originally known as “Miner’s Bathtub,” and later became “Devil’s Hole,” but in the early 20th century, “Devils Hole” started appearing as an alternate spelling on some government documents. Eventually, officials gave way to the inevitable and officially titled the spring “Devils Hole,” much to the dismay of regional grammarians.
These fish are quite small, around the size of minnows, and they turn electric blue during breeding season, with striking black stripes along their backs. In body type, the Devils Hole Pupfish closely resembles other pupfishes, with a large head and pronounced anal fins. They feed on diatoms which are naturally present in the pool, breeding and feeding on a limestone shelf just below the surface of Devils Hole.
In 1890, people first noticed the Devils Hole Pupfish; these fish were identified as a unique species in the 1930s, when around 500 individuals were counted. By the 1960s, researchers recognized that the fish population was declining, and a move was made to protect the pupfish under the Endangered Species Act. This proved to be contentious, as the need to cut back on irrigation to protect the fish cut into the profits of neighboring agricultural concerns. The successful court case paved the way for similar moves to protect endangered species all over the country, and the population began to stabilize.
By 2006, however, the fish population had declined to less than 50 individuals, for no apparent reason. Some individuals were moved to new environments in an attempt to preserve the species, but the abrupt decline of the original population after moves had been made to protect it was puzzling and a source of concern. Some researchers have suggested that the Devils Hole Pupfish is extremely sensitive to changes in its environment, so a subtle shift in water level, temperature, or chemistry might be responsible for the dwindling numbers of fish. Scientists are also puzzled about how the fish got into Devils Hole in the first place, since it is not connected to any known bodies of water.