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Monopterus albus

Asian Swamp Eel

Class: Actinopterygii
Order: Synbranchiformes
Family: Synbranchidae

Photographer: Florida Fish and Wildlife Commission
Source: Copyright: (CC BY 3.0)


Asian swamp eels lack fins and have scaleless, cylindrical bodies with tails that taper at the end. The mouth contains bristle-like teeth and there is a distinctive v-shaped gill on the throat. Overall, the coloration is variations of green, brown, and olive with the ventral side being lighter in coloration. In the U.S., Asian swamp eels are sometimes mistaken for the native American eel (Anguilla rostrata) ; but the Asian swamp eel is not a true eel and belongs to the fish family Synbranchidae. True eels have small pectoral fins and paired gills on each side of the head.

Ecological Threat: Because the Asian swamp eel is a generalist predator that could impact native fishes, amphibians, and invertebrates. However, little is known about the potential negative impacts of Asian swamp eels in areas where they have been introduced.

Biology: When Asian swamp eels are born, they are all females and not until maturation do some later transform into males; this is called sequential hermaphroditism. These species prey on a variety of species from turtle eggs to frogs, shrimp and other aquatic invertebrates. Nocturnal in habit, Asian swamp eels create burrow systems up to 1.5 meters deep to shelter in during the day. Asian swamp eels are capable of moving over dry land, primarily during heavy rains, for short distances because they can breathe atmospheric oxygen for brief periods of time.

History: Introduction is believed to be the combined result of aquarium dumping, releases from fish markets, intentional stocking as a food source, escapes from fish farms during flooding events, and potentially also ceremonial releases. With this species being nocturnal in habitat it is not seen often by humans, so it may be more established in the United States than is known. Known for being a food source in Asia and Japan, this species was introduced by Asian immigrants to Oahu, Hawaii before 1900. Introduction to the continental United States in Georgia was first documented in 1994 and is believed likely the result of an aquarium release. Since the late 1990s, the Asian swamp eel has become established in Florida and in 2008 it was found in Silver Lake in New Jersey. In 2016, Asian swamp eels (Monopterus cuchia) were found in a small lake in the Houston area where they may now be established.

U.S. Habitat: A wide variety of freshwater habitats are used by Asian swamp eels, such as shallow wetlands, stagnant mashes, rivers or even ditches. Also, Asian swamp eels have high salinity tolerance and can be found in brackish and saline waters.


Native Origin: Asia; from India to China

U.S. Present: FL, GA, HI and NJ

Distribution in Texas:



Some studies are testing the use of electrical barriers and vegetation removal in waters where Monopterus albus is present. Removal by electroshocking helps limits this species’ distribution; Prevention is the best form of management and it is important to never release aquarium fish, know whether this is a prohibited species in your state (it is prohibited in Texas), and report sightings both from the wild and, if prohibited, from aquarium/pet stores or markets to your local state agency (for Texas, contact or call your local game warden).

Text References

Hill, J.E. and C.A. Watson. 2007. Diet of the nonindigenous swamp eel in tropical ornamental aquaculture ponds in West-Central Florida. North American Journal of Aquaculture 69:139–146

Maciolek, J. A. 1984. Exotic fishes in Hawaii and other islands of Oceania. Pages 131-161 in Distribution, Biology, and Management of Exotic Fishes The Johns Hopkins University Press.

Shafland, P.L., K.B. Gestring, and M.S. Sanford. 2010. An assessment of the Asian swamp eel (Monopterus albus) in Florida. Reviews in Fisheries Science 18(1):25-39.

Woodward, Susan L., and Joyce Ann. Quinn. "Asian Swamp Eel." Encyclopedia of Invasive Species: From Africanized Honey Bees to Zebra Mussels. Santa Barbara, CA: Greenwood, 2011. 160-62. Print.

Internet References (non-indigenous Aquatic Species)

Online References

SEARCh Online

Google Search: Monopterus albus
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Last Updated: 2021-07-06 by