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A presidential proclamation in 1952 declared the devils hole a section of the Death Valley National Monument. This monument was in 1994 renamed the Death Valley National Park.

In the dry, cracked earth of this national park, there are several creeks and springs. Here, scientists discovered a pupfish species in a water-filled cavern named Devils Hole.

The pupfish belongs to the family of Cyprinodontidae and genus Cyprinodon. The devils hole pupfish belongs to the Cyprinodon Diabolis species. This species was described by scientists in 1930 and is closely related to the Cyprinodon Salinus (Death Valley pupfish).

Male and female devils hole pupfishes have rounded caudal fins but no pelvic fins. Their caudal peduncles are rectangular and short and set at the same levels with their wide-set mouths. The jaws of the devils hole pupfish have 32 teeth. This fish has ctenoid rather than preorbital scales, an elongated anal fin, and large eyes and a head.

The female devils hole pupfish is smaller and thinner than the male, and its dorsal fin has a light spot. It has a yellow-brown body color and no bars on the tail.

The male devils hole pupfish’s tail has vertical bars, and the fish has an iridescent blue body. The fish grows to average adult lengths of 20 mm (0.8 inches).

The following are tidbits to boost your understanding of the devils hole pupfish.

Devils Hole Pupfish  Natural Habitat

The devils hole pupfish is only found in the Devils Hole located in Nevada. This cavern has depths of more than 430 feet (130m). The fish nonetheless only occupies the upper 80 feet (24m), with most of its population concentrated at 49 feet (15m).

This depth is also rich in limestone, and most of the pupfish’s population resides in the limestone shelf. The pupfish spawn on this shelf and rely on it for the fish and their diet that primarily comprises diatoms.

The water in the devils hole pupfish’s natural habitat has a constant temperature of 33 degrees Celsius (91 degrees Fahrenheit). It also has low amounts of dissolved oxygen at 2.5-3.0ppm at around 72 feet depths. The water here is freshwater and the climate temperate.

Devils Hole Pupfish Tank Requirement

The devils hole pupfish is extremely isolated, has a small population number, and is confined to only one natural habitat. It also exhibits unique morphological characteristics. To this end, efforts have increased through the years to preserve its natural habitat and protect the fish.

In the late 1960s, there was a water-pumping activity around the Devils Hole that threatened the pupfish’s survival.

Environmentalists lobbied the government to declare the devils hole pupfish an endangered species in 1982 under the ESA (Endangered Species Act).

This allowed the protection and management of the fish. Since then, scientists have tried to relocate the fish and spawn it in other environments like the San Francisco-based Steinhart aquarium.

Even so, the efforts for maintaining the devils hole pupfish in aquariums have been mostly unsuccessful. Another attempt to rear the pupfish in the Hoover Dam was successful, but the pupfish here exhibited abnormal growth patterns not seen in their natural habitats.

As such, the devils hole pupfish only lives in its natural habitat. Moreover, as an endangered species, this fish is unavailable for hobby aquarists.

Devils Hole Pupfish Water Conditions

Despite the best efforts of scientists, mirroring the water conditions in the devils hole pupfish’s natural environment is almost impossible. Research is ongoing on the ideal water parameters for this fish outside their natural habitat.

Devils Hole Pupfish Diet and Feeding

The devils hole pupfish is an omnivore that primarily feeds on algae growing on the limestone shelf of its natural environment.

The diatoms are their primary diet in the winter and spring, while in fall and summer, the fish feed on spirogyra. The pupfish nonetheless also feeds on mollusks, aquatic crustaceans, marine or aquatic worms, and other marine invertebrates.

Devils Hole Pupfish Tank Mates

The devils hole pupfish is an energetic and lively fish that will sprint around its natural habitat. It is the only member of the Cyprinodontidae family that has no territorial tendencies.

The pupfish is the largest inhabitant of the Devils Hole, and there are no dominant species that live with it. Moreover, being at the top of the food chain in its habitat, the devils hole pupfish has no predators.

Devils Hole Pupfish Breeding

Breeding the devils hole pupfish in captivity has been mostly impossible because the conditions do not precisely match those in its natural habitat. In the wild, the fish lives for 6-12 months. The pupfish breeds all year round though the intensity increases between April and May.

During reproduction, several males will follow a lone female until the fish becomes receptive. The male and female will move to the pool’s bottom for spawning. The limestone rock in its natural habitat and the algae on it are the substrates for spawning.

It takes a week for the eggs laid to hatch into fry with lengths of 6.5mm. Research has not shown any parental investment in the fry after spawning. The devils hole pupfish reaches reproductive age in 8-10 weeks after hatching.

The low population levels of the devils hole pupfish are, at times, attributed to the low reproduction levels in the females. The average female only produces 4-5 mature egg cells in a breeding season.

During each spawn, the female produces one egg that has a low hatching success. Other than these, the rates of survival for the fry of the devils hole pupfish are low.

Wrapping Up

The above tidbits are only part of what constitutes the devils hole pupfish. Its mysterious beginnings, delightful pup-like movements, and incredible living circumstances make it an exciting fish for you to follow.

While its population has been dwindling, new strides are being made in the research on devils hole pupfish to ensure that this species does not become extinct.

It now remain a leading example of the animals being protected in designated spaces. Maybe in a few years, they will become a part of aquariums to allow millions worldwide to enjoy its beauty.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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