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Current invaders:
Crustaceans: Rusty Crayfish | Spiny Water Flea
Fish: Goby (Round) | Goby (Tubenose) | Rudd | Ruffe | Sea Lamprey | White Perch
Mollusks: Quagga Mussel | Zebra Mussel
Plants: Curly-leaf Pondweed | Eurasian Watermilfoil | Phragmites (non-native) | Purple Loosestrife
Viruses: Viral Hemorrhagic Septicemia Virus (VHSv)
Potential invaders:
Fish: Asian Carp

[Invasive species home page]

What's New
Evil minnow discovered in Ontario inland lakes
SooToday (1/23)
The rudd, a type of European minnow and an invasive fish believed to be spread through the dumping of bait buckets, has been found for the first time in an inland Ontario lake.

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The rudd (Scardinius erythrophthalmus), is a cyprinid fish (in the minnow family) native to Europe. It is believed that the rudd was originally imported into the United States from Europe as a food and game fish in the early 1900s. Since its introduction, the rudd has been commonly used in aquaculture operations and as bait, contributing to its spread.

Although the rudd prefers to live in stagnant and slow-flowing freshwater with thick vegetation, it can adapt to other environmental conditions, including poor water quality. It is an omnivorous species that lives up to 15 years, with feeding habits shifting as individuals mature; young feed on algae and small invertebrates, while adults feed on aquatic vegetation and insects. This characteristic enables rudd to compete broadly with native species for available resources. Since rudd do not process vegetation effectively, they tend to increase the amount of nutrients in the water as the undigested organic matter is expelled.

Environmental impact: impact caused by the rudd's introduction into the Great Lakes is largely unknown.  Aside from general competition with native species for resources, nutrient load increases caused by its incomplete digestive processes may result in localized algal blooms and other changes in water quality. Also, the rudd is capable of breeding with the native golden shiner, resulting in hybrid offspring. It is unclear how this "genetic pollution" will impact subsequent generations of the native fish.

Photo: Brian Gratwicke

For complete overview, identification and management:
View full, print-ready factsheet

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Distribution Maps
Geographic information on the location of aquatic invasive species sightings in the United States is made available through the U.S. Geological Survey, Nonindigenous Aquatic Species (NAS) program.

NAS distribution maps for Rudd

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Studies, Assessments and Management Plans
Biology and potential impacts of rudd (Scardinius erythrophthalmus) in New Zealand (2006)
Brendan J. Hicks. Hicks provides an overview of the introduction, biology and impacts of the rudd in New Zealand.

Implications of Rudd (Scardinius erythrophthalmus) Herbivory on Submerged Macrophytes in a Shallow Eutrophic Lake (2003)
Hydrobiologia (2003)
Nurminen, L., J. Horppila, J. Lappalainen, and T. Malinen.(Abstract) The role of rudd herbivory is studied in Kirkkojarvi, a shallow and turbid basin in Lake Hiidenvesi, Finland.

Population Assessment of Rudd (Scardinius erythrophthalmus) in Presque Isle Bay, Lake Erie (2005)
Pennsylvania State University
The purpose of this study was to provide an initial population assessment of rudd in Presque Isle Bay, Lake Erie in order to better understand the potential effects that the non-native fish has on this Lake Erie ecosystem.

Predicting Future Introductions of Nonindigenous Species to the Great Lakes (2008)
U.S. Environmental Protection Agency
This report maps the Great Lakes habitats most susceptible to the entry of AIS. 58 potential invaders, including rudd, were identified as posing high or medium risk for becoming established – and for causing ecological harm – in the Great Lakes.

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U.S. and Canadian Federal Resources
Rudd Fact Sheet
U.S. Geological Survey - Nonindigenous Aquatic Species

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State and Provincial Resources
A Field Guide to Fish Invaders of the Great Lakes Region
University of Minnesota Sea Grant Program

Eurasian Rudd (Scardinius erythrophthalamus) Fact Sheet
New York Sea Grant

European Rudd (Scardinius erythrophthalamus)
University of Wisconsin Sea Grant Institute

List of Injurious Species
Illinois Department of Natural Resources

Prohibited and Restricted Species
Michigan Sea Grant

Rudd (Scardinius erythrophthalamus)
Ontario Federation of Anglers and Hunters

Rudd Fact Sheet
Pennsylvania Sea Grant

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Updated: December 11, 2017
Selected Photos: Copyright ©John and Ann Mahan
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