ARK - Arizona Rivulin Keepers

Some Observations on The Desert Pupfish, Cyprinodon macularias

by Allan Semeit

[part of this article was originally published in JAKA, Nov/Dec 1990.  That article has been expanded and updated.]

When I joined the American Killifish Association in the early 1970s, several members of the Bay Area Killifish Association were actively breeding pupfish.  One of these was Al Castro who, at the time, worked with the freshwater fishes at California Academy of Sciences, Steinhart Aquarium.  Al encouraged me to give pupfish a try.

One result of this encouragement was a 1973 Salton Sea pupfish collecting trip.  I was able to obtain a scientific collecting permit from the state of California through the Aquatic Research Institute.  Al Castro provided the directions to an area known as the Cleveland Canal.  The story of that trip can be found in "In Search of Cyprinodon macularias," Killie Notes (American Killifish Association), 1973, 6 (10):18-19.

The Desert Pupfish, Cyprinodon macularias, was the target of that trip.  At that time, this species was common around the Salton Sea.  A March 1980 study by Black points this out (see website reference #3 below).  I was able to obtain breeding stock from that trip and maintained this strain for about 24 years.

Someone once asked me why I enjoy keeping the Desert Pupfish.  After watching them, it's not hard to be fascinated by them.  They remind me of a bulldog.  They have a pug lip, big head, and a bulky body, much higher that it is wide.  Yet, in my experience, they are not as aggressive or territorial as some other species of pupfish.   Some endearing qualities of C. macularias are that they are active, not overly shy, and come to recognize the hand that feeds them.  They have personality.

The Desert Pupfish also has a pretty side. Males in breeding color are turquoise blue with yellow to orange colored tail fins.  Pictures do not capture the true colors, but the Desert Ecology website has a photo that tends to show turquoise blue of male Macularias (see website reference #10).  Al Castro (1980) considers the Salton Sea variety of Cyprinodon macularias to be the second most intensely colored pupfish in the hobby, after Cyprinodon eremus (formerly considered to be a population of C. macularias from Quitoboquito Springs (see website reference #6 for an excellent color photo of C. eremus).  The colors of wild males have always been more intense than those of aquarium fish. Castro also noted that the Desert Pupfish needs extra vegetable matter in its diet and needs an extra long photo period (14-16 hours) for best color.  Joe Anascavage (1972) underscores the necessity of light for all pupfish and states that 18 hours per day is the optimum for both breeding color and egg production.  I've tried color-enhancing foods like krill and spirulina, but have never matched the wild colors.  I have even kept pupfish outside year round to see if sunshine and natural food supplements would make a difference.  No luck, although I know pupfish are hardy.  They have survived water temperatures in the high 90s to water with an inch of ice on it for three days.

Care for pupfish, and most other North American killies, differ from African killifish, in several ways.  First, they require larger containers.  Most adult native killies will not thrive in any tank less than ten gallons, and the bigger the better.  For many years, my best success with the Desert Pupfish came with a group spawning set-up using a 22-gallon breeder flat tank (24x20x12").  Although the numbers varied, I liked to keep a minimum of five females and three males together, but preferred having about fifteen in the breeding tank.  This eliminated any serious aggression and kept the females from getting too much attention. While pupfish are extremely hardy, you still need to make regular water changes and provide a healthy environment.  Pupfish need alkaline water conditions to thrive and regular water changes can prevent the water from becoming acidic.

An other set-up that works for some pupfish are plastic sweater boxes.  My favorite size has been the ones that measure approximately 23x15x7 inches.  The seven inch depth has actually worked better than a same-sized box with a nine inch depth.  The shallower water may limit visibility and reduce male aggression.  There is less water in these sweater boxes, compared to a ten-gallon tank, so frequent water changes are highly recommended.  For spawning, I use at least two, preferably three, 70 strand floating mops.  Filtration can be challenging.  I have used a variety of submersible power filters and they work,  but I keep coming back to the old air-driven box filters (containing gravel, such as dolomite or crushed coral, and sponge).  To create a modest water flow, I have added an elbow at the top of the return stem.

The sweater box set-up has worked with the less territorial species such as C. macularias and C. fontinalis.  My experiences with more territorial species such as C. veronicae indicate that success with them requires even larger habitats.

The killifish breeder will discover that there is a tremendous difference between the Desert Pupfish and African killies in the area of feeding.  Pupfish love to eat.  I can't remember them turning up their noses at any food I offered them.  Anascavage (1972) comments that "their unsatisfying appetites require feedings up to 7 times daily... (although he) recently decreased (his) feedings to 5 times daily..."   Although I haven't tried it, pupfish act like they're ready to eat every five minutes.  Like other fish, multiple light feedings throughout the day are best.

Because it is so convenient, my major food is flake food.  I prefer the spirulina flakes because algae seems to make up a high proportion of their natural diet and spirulina contains color enhancers.  I like to mix my flake foods and recommend you add a basic type flake food to the spirulina.  In addition, my pups get occasional live brine shrimp, tubifex, and daphnia, as well as freeze-dried bloodworms and krill.

Like their parents, the fry like to be fed often and are not fussy. Joe Anascavage states that the "months of experiments have proven that the greatest number of fry are raised if microworms are used as their first food for at least two weeks.  Feeding should be at least twice daily." Anascavage recommends that after two weeks you can start them on baby brine shrimp and powdered flake foods.  To be honest, I've never noticed any problems starting the fry with baby brine shrimp.  One possible answer for this difference in experience may be due to the size variations between populations of brine shrimp.  For years, my baby brine shrimp were from the San Francisco bay and they hatch out much smaller than brine shrimp from the Great Salt Lake.  Lately, I have been using Great Salt Lake brine shrimp with success.  I also like to add Java Moss to the rearing containers and, when available, add drops of green water as a food supplement.

The greatest challenge to successfully raising the pupfish fry may be feeding them enough, while at the same time keeping their water clean.  Excess waste and uneaten food can quickly pollute the water, as well as acidify the water. Regular small water changes are necessary.  Another tip is to place either a piece of Poly Filter in the water or add some ammonia-neutralizing crystals such as those made by Marineland.  These adsorb a number of harmful substances (they also work well in all small fish containers).

Pupfish spawn readily in a mop. While some breeders have success with a bottom mop, my best results have been with a floating mop. When the water is circulating, I use a clothes pin attached to one of the strands to hold it stationary.  The mop should hang down to almost the bottom, or, if you have a bare bottom tank, can extend to the bottom and then some. Surprisingly, most of the eggs are found within an inch of the waterline. One surmise for this is that the mop strands nears the waterline are bound tighter together, which may offer more protection to the eggs from hungry parents.  While I've never witnessed egg predation, I'm fairly certain that it occurs in my group spawning set-up.  Otherwise, I'd be up to my eyeballs in fish.

Jim Hirsch (1977) noted that he found most of his eggs quite close to the top of the spawning mop.  He reports that he had "heard that this is natural, because they generally do most of their spawning near the surface (despite their propensity for bottom crawling), and they also enjoy dining on the eggs they find near the bottom of the mop."  If you've seen pupfish spawn on duckweed, you can believe that they like to spawn near the surface!  This might also partly explain why I collected more pupfish in the shallowest water at the Salton Sea rather than in the slightly deeper parts

I've found that there are few eggs produced when the temperature is below 75 degrees Fahrenheit.  My guess is that somewhere around 78-86 degrees F is the most productive range, but watch out for oxygen depletion at the higher temperatures.  Castro (1976) did a study of egg production with several subspecies of Cyprinodon nevadensis and found that the Tecopa Bore population achieved its highest production at around 90 degrees F, while those from the Amaragosa River and Saratoga Springs populations peaked at 80 degrees F.

Desert Pupfish seem to mature just a bit more slowly than some of their cousins.  This may be a response to the wide range of habitats where C. macularias is found (Flather, 1975).  In contrast, many other species of Cyprinodon live in very restricted habitats.  For example, the Tecopa Bore population of C. nevadensis, which inhabits a series of hot spring pools, may reach sexual maturity within one month of hatching and there may be as many as ten generations per year in the pools (Stolz and Naiman, 1978).  This accelerated growth is usually accompanied by a seasonal lifespan of one year or less.  Desert Pupfish, perhaps because of their slower growth, are one of the largest pupfish, reaching about three inches.  They also live longer than most, typically about two years.  Desert Pupfish reach a sexual maturity at a length of about one inch in approximately six months.  From this point, they are capable of spawning until near death.

Cyprinodon macularias is a better community fish than some of its relatives.  I've kept other natives, such as Fundulus cingulatus and Red Shiners, with the Desert Pupfish, even spawning them together and raising the fry in the same rearing tanks (with some separation according to size).  I have even thrown some extra Aphyosemion striatum males and occasional oddballs into a 55-gallon tank of juveniles and all have co-existed peacefully.

After this list of attributes and experiences, you can see why I've enjoyed keeping the Desert Pupfish all these years.  Try them, I think you'll like them.

Literary References

Anascavage, J. 1972.  The Sensuous Pupfish,  Killie Notes, 5(4):14-17. Castro, A.D.  1976.  Killies of the Southwestern United States - Cyprinodon nevadensis, J. Am. Killifish Assoc., 9(8):225-230.
Castro, A.D.  1980.  Tips on Maintaining Western Pupfish,  J. Am. Killifish Assoc., 13(6)-158-162.
Flather, E.  1975.  An Outline of the Genus Cyprinodon, J. Am. Killifish Assoc., 8(8): 229-234.
Hirsch, J.  1977.  Cyprinodon macularias, Golden Gate Aquarist, January 1977.
Semeit, A.L..  1973.  In Search of Cyprinodon macularias, Killie Notes, 6(10):18-19.
Stolz, D.L. and R.J. Naiman.  The Natural History of Native fishes in the Death Valley System, Natural History Museum of Los Angeles County; 1978.

Web References

1.  Fishbase website - a brief description of Cyprinodon macularias:

2.  Desert USA website with pupfish information and a photo of a male pupfish (Macularias?):
  3.  March 1980 study of Salton Sea pupfish populations by Black:
  4.  September 1993 review of the status of desert Pupfish by Andrews and Brown:

5.  August 1999 study of the Desert Pupfish by Sutton for the Salton Sea Authority:

6.  Pima County, AZ, description of the endangered Desert Pupfish:

7.  Fish in the Desert? by Keeney (excellent color photo of female pupfish):

8.  2001 (?) Coachella Valley Multiple Species Habitat Conservation Plan: Pupfish

9.  Pima Community College - brief description of Pupfish with excellent color photo of  C. eremus:

10. Desert Ecology website with Pupfish color photo - tends to show turquoise blue of male Macularias:

11. National Parks Conservation Association website article on C. eremus:

12. California Department of Fish and Game website status of Cyprinodon macularias:

13. Environmental Defense website on Arizona Fish Safe Harbor Agreement: