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Texas Invasive Species Institute

Texas Invasive Species Institute

Monogenean gill worms

Pseudodactylogyrus bini

Class: Monogenea
Order: Dactylogyridea
Family: Pseudodactylogyridae

Pseudodactylogyrus bini

Photographer: unknown Affiliation:Database of Parasites in Fish and Shellfish Source:www.fishparasite.fs.a.u-tokyo.ac.jp Copyright: D-PAF


Pseudodactylogyrus bini is a monogenean gill worm that infects the invasive European eel (Anguilla anguilla) and native American eel (Anguilla rostrata). This monogenean feeds on mucus, epithelial cells, and cells reacting to the infection (blood from haemorrhaging). Eels produce weak antibodies in response to infection from P. bini often resulting in fatality or other detrimental results.

Symptoms: Infected eels can face serious effects including mortality and slowed maturity related to reproduction. Pseudodactylogyrus bini feeds on mucous and epithelial cells causing a haemorrhage inside the eel body. This results in hyperplasia of gill tissue and can be so detrimental that haptor and hindparts become embedded.

Host(s): Anguillid eels

Ecological Threat

The eel trade has been consistently popular since the 1900's creating profit from eel sales and cultivation of eel farms. This trade provides regular transfers of eels allowing for a concurrent transfer of P. bini. Due to the serious side effects of infected eels, the eel trade faces serious economic losses due to high mortality of infected eel farms. This monogean also creates a threat to native eel populations in the wild that are already facing a dramatic population decline due to anthropmorphic factors.


Most monogeneans have a simple life cycle consisting of an egg, larval, and adult stage. Eggs hatch as an Oncomiracidia, which is an elongate cell bearing cilia. The oncomiracidia is a free swimming stage that is relatively short with attachment to a host triggering loss of cilia and development into the adult  form. Many monogeneans have evolved life cycles that coincide with host life cycles to increase chances of contact during the free swimming stage. For example the monogenean will breed near the time of the host spawning causing the number of potential hosts to increase in an area.


Japanese eels (Anguilla japonica) were first documented with infection by P. bini 70 years ago. Due to eel migrations  and trade facilitating the transfer of this monogean, European eels were infected in the 1980's followed by the American eel in the 1990's.

Native Origin

Native Origin: Japan

Current Location

U.S. Habitat: Pseudodactylogyrus bini is dependent on a host for survival and can be found infecting a host. The host, aguillid eel, is found off the east cost and gulf coast in the U.S. and in bodies of water as far west as the Great Lakes.

U.S. Present: GA, SC 

Texas: No reports  


There is currently no cure or remedy to kill the  parasite without harming the host. The aguillid eel host also lacks natural immune defenses strong enough to treat infection. The only current management techinque is to prevent infected eels from exposue to healthy eels. It is also important to alert local wildlife authorities if there is a potential for an infected eel in your area to prevent further spread to other native eels.   



Buchmann, K. 1988. Feeding of Pseudodactylogrus bini (Monogenea) from Anguilla anguilla. Bulletin of European Association of Fish Pathology 8: 79-81.

Buchmann, K. 1997. Infection biology of gill parasitic monogeneans with special reference to congeners Pseudodactylogyrus bini and P. anguillae (Monogenea: Platyhelminthes) from European eel. Dissertaion, Royal Veterinary and Agricultural University, Frederiksberg.

Carlton J.T., and J.B. Geller. 1993. Ecological roulette: the global transport of nonindigenous marine organisms. Science 261: 78-82.

Hayward, Craig J., Makoto Iwashita, John S. Crane, and Kazuo Ogawa. 2001. First report of the invasive eel pest Pseudodactylogrys bini in North America and wild American eels. Diseases of Aquatic Organisms 44: 53-60.  

Marcogliese, D.J., and D.K. Cone. 1993. What metazoan parasites tell us about the evolution of American European eels. Evolution 47: 1632-1635.

Roberts, Larry S., and John Janovy Jr. 2000. Foundations of Parasitology. McGraw-Hill Higher Education: New York. 6th ed.

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