LABORATORY REARING OF THE DESERT PUPFISH, Cyprinodon macularius 



David Crear' and Irwin Haydock^ 



ABSTRACT 



The desert pupfish, Cyprinodon macularius, may ba reared in the laboratory for use in the study of 

 embryology, genetics, physiology, and behavior. It is euryhaline (0-70 %c) and eurythermal (8°-44.6° C) 

 and may be useful as a bioassay for either freshwater or marine pollutants. In the Salton Sea area 

 of California, the recent introduction of exotic species and the encroachment of civilization have 

 drastically reduced the formerly abundant pupfish populations. Laboratory rearing eliminates the need 

 for continuous exploitation of a rapidly contracting natural population and could supply adequate stocks 

 for sanctuaries, thereby preserving the species from extinction. Laboratory apparatus and conditions 

 are described for maintaining larval and adult pupfish. Parasites and diseases encountered are dis- 

 cussed and successful treatments described. Methods for spawning and rearing the desert pupfish in 

 the laboratory are detailed. These methods may also be applicable to many other species of pupfish 

 that are in danger of extinction. 



The desert pupfish, Cyprinodon macularius 

 Baird and Girard, is a killifish (Cyprinodonti- 

 dae) native to the Lower Colorado River Basin 

 from southern Arizona to southern California 

 and the Sonoyta River of northern Sonora, Mex- 

 ico (Miller, 1948). It thrives under the harsh 

 conditions of the desert environment. It lives 

 in fresh water as well as highly saline pools 

 that few other vertebrates can tolerate. Its 

 ability to survive in such environments, plus 

 other important biological characteristics listed 

 in Table 1, renders it an exceptionally hardy 

 laboratory animal potentially valuable for re- 

 search in many fields. 



POTENTIAL FOR RESEARCH 



Desert pupfish has many characteristics fa- 

 vorable for embryological research. It can be 

 spawned with relative ease and can be main- 

 tained in the laboratory throughout the year 

 to supply large eggs (approximately 2 mm in di- 

 ameter) , suitable for vital marking and grafting 



' Formerly, California Department of Fish and Game, 

 Inland Fisheries Branch, Sacramento, Calif.; present 

 address: School of Public Health, 1890 East-West Road, 

 University of Hawaii, Honolulu, Hawaii 96822. 



' Formerly, California Department of Fish and Game, 

 Inland Fisheries Branch, Sacramento, Calif.; present 

 address: Southern California Coastal Water Research 

 Project, 10845 Lindbrook Drive, Los Angeles, Calif. 

 90024. 



Manus<!ript received September 1970. 



FISHERV BULLETIN: VOL. 69. NO. 1. 1971. 



experiments. Other favorable characteristics 

 are the transparent chorion and the long devel- 

 opmental period which can be temperature-con- 

 trolled (New. 1966). The sticky filaments that 

 are attached to the chorion of its demersal egg 

 can be partially removed by rolling the eggs 

 gently on filter paper 4 to 8 hr after fertiliza- 

 tion. Any remaining filaments are matted to- 

 gether and can be easily removed with small 

 forceps. 



Desert pupfish, since they mature quickly, 

 could be used for research in fish genetics and 

 on the aging process. Barlow (1961) reported 

 that pupfish reach maturity in the field in 3 

 months. F, pupfish, reared from eggs and 

 maintained at 27° C, were observed spawning 

 in the laboratory approximately 4 months after 

 hatching. 



The desert pupfish, a euryplastic species, also 

 possesses physiological and behavioral traits that 

 make it valuable for scientific research. The 

 juveniles can tolerate salinities ranging from 

 fresh water to 90 <,;, (Barlow, 1958). The 

 adults, although less euryhaline, are known to 

 spawn in salinities as high as 70 %r (Kinne and 

 Kinne, 1962). The salinity tolerance of newly 

 hatched pupfish render them potentially useful 

 for comparative bioassay of freshwater and 

 marine pollution. The extreme temperature tol- 

 erance is an additional asset. Desert pupfish 



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