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The silver-colored pupfish have evolved over the years and have learned to adapt to change. Once thriving in the streams and lakes that filled Death Valley over 250 million years ago, this fish got stranded in some few springs as major streams dried up.

Due to being stranded in isolated places, the pupfish evolved into subspecies, with each type having different adaptations. Some groups reign supreme over others.

For instance, the Devils Hole pupfish can withstand very hot temperatures, even as high as 90 °F. Other localized subspecies are unique, too. 

Amidst the dry Death Valley National Park, there are still some creeks and springs where one may find one of the five types of pupfish. The pupfish is a bright, silver-blue, small fish with a tiny body of a goldfish and a flat head of a pike.

The fish earned their name because of their playful nature, especially how they frolic about like puppies. 

Death Valley Pupfish Natural Habitat

Being one of the rarest fish, the pupfish can spend most of their lives in very hot water in the middle of the Mojave Desert. In fact, its habitat is one of the smallest natural ranges that any vertebrate can survive in.

To say the least, the Death Valley pupfish can survive in extreme environments, with dissolved oxygen concentrations and water temperatures lethal for fish. This fish has survived and adapted to these harsh conditions over a long period of time. However, they can only live up to 2 years.

The Death Valley is composed of separate areas. One is composed of unknown depths of limestone rock, which the other has a limestone rock shelf that is 3.5 meters deep. 

Death Valley Pupfish Tank Requirements

These fish can adapt to most home aquarium conditions, but they do best in a brackish environment. For this reason, they might be ideal for fish keepers with years of experience under their belts.

Having said that, these fish can live comfortably in a 15 or 20-gallon aquarium, with a bit of tight fighting lid. Try to set up a brackish environment, by adding a bit of salt into the aquarium. On top of this, provide some good filtration systems.

If you live in colder climates or if it is winter, try to have a heater to keep the water temperature warm. Though optional, you can use a powerhead to create water movement. The good thing is that these fish can adapt easily to many aquarium environments.    

As you set up your aquarium consider that the Death Valley pupfish will swim in the middle to lower parts of the tank. They also appreciate it if you provide them with a soft substrate so that they can dig into them and hide.

With this in mind, you can provide fine gravel substrate and then top it up with some reed type plants to mimic their natural habitat. Low to moderate lighting will spruce up things. It will make the fish feel at home. 

Because they come from constantly changing habitat, there is no one way to set up your tank. On average, you need a tank with a minimum size of 20 gallons. A Nano tank might be ideal for them.

The right type of substrate for this fish is sand, as long as you keep the temperatures at about 25.0 to 35.0° C. Besides this, maintain a water pH level of 7.5 – 8.0. And yes, you need to make it brackish. The harness range can be between 13 to 19 dGH. Water movement can be moderate or you can just live it the way it is. 

While constructing the tank, it is also important to pay attention to some of their social behavior. For instance, the Death Valley pupfish can excel in a community tank with other fish. We will discuss in detail about their tank mates in a later section. 

Death Valley Pupfish Water Conditions

As mentioned above, the Death Valley pupfish is a desert species. They can survive in stern conditions. They can survive naturally in hot springs and water holes with extreme temperatures, even as high as 45° C.

Most of them can also live in water with high salt concentrations up to six times more than the ocean salinity. So, it is safe to say that the pupfish can survive in most aquariums. In the winter when the water becomes colder, this pupfish can still survive.

In most cases, it becomes dormant and buries into the muddy bottoms to hide there. So, they can survive in both extremes, but they enjoy high temperatures more than colder conditions. The right aquarium hardiness is moderately hardy.   

Keep in mind that these fish come from desert-like environments, so you might need a heater to warm up the water if the temperature falls below 68° F. Otherwise they will be forced to hibernate in cold water.

In fact, with this fish, you might need to use about two heaters to ensure constant temperature just in case one break. Basically, you need to do anything to make them happy and healthy. Besides this, change the water in the tank on a weekly basis. 

Death Valley Pupfish Diet and Feeding

The Death Valley pupfish are omnivorous by nature, so they can feed on most aquatic foods such as detritus, algae, and aquatic invertebrates. Any food that contains shrimps, fishes, worms, and other meaty food would suit this fish.

They can also survive on some vegetable food and flake food. Just like most fish, the Death Valley pupfish can feed throughout the day. So you need to feed them several times a day. 

Death Valley Pupfish Tank Mates

Because they can survive in extreme conditions, there are a few species that can live comfortably with them if you were to maintain the same conditions as their natural habitat. However, this fish is a social animal.

In fact, they will do best when you keep them with other Pupfish, especially those of the same genera. Splitfins like Empetrichthys can cohabit comfortably with the Death Valley pupfish.

With that said, male pupfish are usually loners. In their natural environment, they will dig a shallow depression to hide or rest in. they don’t like intruders, especially when in breeding mode.  

Generally, they are peaceful, non-venomous fish that love to socialize with other similar fish, though male pupfish can be territorial sometimes. 

Death Valley Pupfish Breeding

Male and Female Death Valley Pupfish (source)

 

The Death Valley pupfish exhibits a polygynous breeding system, defined as a gravid female being chased close by one or more males. These males follow the female pupfish periodically, who loves to move to the bottom of the tank and spawn.

While each male will prevent other competing pupfish from getting close to the female by blocking the competing male with his body. Actually, male pupfish can exhibit a bit of aggressive behavior, especially when mating. 

The best thing is that these fish can breed year-round, but most of the breeding happened between April and May. This fact is supported by the constancy of the temperature of their habitat, which remains high at around 33 degrees.

Because of their small population, spawning rates are higher than those of other fish species. Figures show that an average male could experience 0.6 spawning per male each hour, with a maximum of 1.5 spawning per male each hour. This fish uses the algae and limestone bedrock as a substrate for spawning.

On average, the Death Valley pupfish reach reproductive age at around 8 – 10 weeks, but the eggs take about a week to hatch. The average length of fry is 6.5 mm.

Another interesting thing is that male might not display their territorial behavior quite easily, but when the population size and food supplies are lower, they are likely to exhibit such behaviors. 

Generally, the Death Valley pupfish like to breed when the temperatures are high. During this period, the male becomes brightly colored besides defending their territory from all but a receptive female. Their courtship ritual is usually short.

Afterward, the female lay one egg on the bottom of the substrate. As usual, the egg adheres to the substrate before the male fertilizes it. On a typical season, a female pupfish can lay hundreds of eggs, of course each singly. 

With this knowledge, you should be happy to know that these fish can breed comfortably in a small tank, provided you maintain the right conditions. For the best outcome, keep male and female in separate for a number of days, and then introduce them together into the breeding aquarium.

Once the egg has been fertilized, it would take about 6 – 10 days to hatch. The larvae will start to shoot up a day after the hatching. Also note that the newly hatched fry need to be fed infusoria, newly hatched baby brine, or liquid fry food. The fry will grow fast and will reach maturity in less than three months. 

Conclusion

The Death Valley pupfish are extremely hardy, meaning they can survive in harsh conditions. For this reason, diseases are not usually a problem. Moreover, they consume a variety of food and can live comfortably in most home aquariums.

With that said, there is no guarantee that you won’t have a hard time raising them. It is even worse when you know that they are an endangered species.  

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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