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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Fundulidae
Genus: Fundulus
Species: F. heteroclitus
Binomial name
Fundulus heteroclitus
(Linnaeus, 1766)

The mummichog, Fundulus heteroclitus, is a small killifish found in the eastern United States and in Spain (Marismas de Isla Cristina). Also known as mummies, gudgeons, and mud minnows, these fish are found in brackish and coastal waters including estuaries and salt marshes along the eastern seaboard of the United States as well as the Atlantic coast of Canada. It is noted for its hardiness and ability to tolerate highly variable salinity, temperature fluctuations from 6 °C to 35 °C (43 °F to 95 °F), and for its ability to withstand very low oxygen levels, a wide variety of toxins, and survive in heavily polluted ecosystems. The mummichog is a popular research subject in embryological, physiological, and toxicological studies.

The two subspecies are:


Mummichogs are typically found in muddy marshes, channels, and grass flats along coastal areas. They travel in schools that may contain hundreds of individuals. Indeed, the name mummichog is derived from a Narragansett term which means "going in crowds".[1]

The mummichog spawns on new and full moons in the spring and summer. Its eggs are laid near the high tide mark in empty mollusk shells or on dead vegetation, and can tolerate long-term exposure to air. Typically, mummichogs reach sexual maturity during their second year and live for a total of three years.[2]

Because of the extreme hardiness of the species, it is sometimes the only species found in severely polluted and oxygen-deprived streams, such as the Elizabeth River in Virginia, and the Hackensack River and the Arthur Kill in New Jersey during the height of the water pollution problem in the United States.[citation needed]

Mummichogs are hosts to a parasitic fluke, Homalometron pallidum, which has a complex lifecycle which also involves the aquatic snail, Ecrobia truncata.[3]

Interest to humans[edit]

Mummichogs are of interest to humans because:

  • Their eggs are used in teaching embryology, because the eyes, the beating heart, and the different stages of ontogenesis can be seen.
  • They are commonly used in toxicology studies.
  • They are used to stock otherwise fishless ponds that breed mosquitos, and within three days, the ponds are normally mosquito free.
  • In 1973, the mummichog became the first fish in space when carried on Skylab 3 as part of the biological experiments package. Later space missions by the U.S., such as Bion 3, have also carried mummichog.
  • They are often caught in seines and minnow traps to be sold as live bait for fishermen.



  1. ^ "Mummichog." Merriam-Webster, n.d. Web. 6 Feb. 2014. <>
  2. ^ Murdy, Birdsong, Musick: Fishes of Chesapeake Bay (Smithsonian Institution Press, 1997), 128
  3. ^ Stunkard, Horace W. (1964). "The morphology, life history and systematics of the digenetic trematode Homalometron pallidum Stafford 1904". The Biological Bulletin 126 (1): 163–173. doi:10.2307/1539426. 

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