Rudd (Scardinius erythrophthalmus)

Photo of rudd by USGSPhoto by Noel M. Burkhead - U.S. Geological Survey

Description

Appearance

From US Geological Survey Nonindigenous Aquatic Species (USGS NAS) database:

"The rudd is a somewhat stocky, deep-bodied fish with a forked tail. The mouth is distinct with a steeply angled protruding lower lip. The scales are robustly marked, the back is dark greenish-brown, and the sides are a brassy yellow tapering to a whitish belly."

Body Shape and Fins

From USGS NAS database:

"The pectoral, pelvic, and anal fins are bright reddish-orange, and the dorsal and tail fins are reddish-brown. Rudd can be distinguished from all native North American minnows (Cyprinidae) by the presence of a scaled keel along the belly between the pelvic and anal fins, along with a deep, compressed body."

Biology

From USGS NAS database:

Rudd is a bottom-dwelling fish of the minnow family that prefers water up to 3 meters deep and temperatures between 2°-22°C (35°-72°F). Abundance decreases with depth, and populations benefit from artificial and natural coastal refuges that help them avoid predation. They can thrive in both flowing and still water environments. Rudd has omnivorous feeding habits that can change with temperature and season. Generally, their diet includes aquatic plants and algae, while sometimes eating invertebrates and small fish. Reproduction occurs from April to August, typically beginning once water temperatures exceed 16°C (60°F). Adhesive eggs are laid among submerged vegetation in warmer, calmer waters near shore. Fecundity ranges from 3,500–232,000 eggs. Maturation occurs at 2 to 3 years when the fish is 90 to 150 mm (3.5”-6”) in total length. Rudd can live to 17 years.

Origin and Spread

From USGS NAS database:

Rudd are native to Western Europe to the Caspian and Aral Sea basins. Rudd have been introduced through a combination of bait bucket releases, escapes from aquaculture facilities and farm ponds, and, presumably, by natural dispersal from various points of intentional introduction. No populations are known to be established in Minnesota, although they have been captured close to the state border in South Dakota, and in the Mississippi River in northern Illinois. Refer to EDDMapS and USGS NAS for current distribution.

Don’t be fooled by these look-alikes

Rudd can look similar to Minnesota's native minnows. Golden shiner in particular bears a resemblance to rudd. However, no native minnows have the rudd’s scaled keel (sharp ridge on the belly) paired with a deep body shape. Rudd also have red, red-orange, or reddish-brown fins, and a red spot on the iris of their eye, while golden shiners tend to have yellow-green fins and eyes.

Look alikes:

Regulatory Classification
Rudd (Scardinius erythrophthalmus) is a prohibited invasive species in Minnesota, which means it is unlawful (a misdemeanor) to possess, import, purchase, transport, or introduce this species except under a permit for disposal, control, research, or education.
Threat to Minnesota Waters
Rudd cause recreational, economic and ecological damage—changing how residents and visitors use and enjoy Minnesota waters.

Rudd impacts:

  • Can outcompete native fishes for food. Their ability to switch from eating invertebrates to fish to plants make them very effective competitors.
  • Disrupts native fish habitat through consumption of aquatic vegetation.
  • Could increase turbidity by stirring up the sediments when feeding, resulting in a decline in water quality.
  • Can hybridize with native golden shiner, with unknown impacts on golden shiner populations.
What You Should Do
People spread rudd primarily through the improper use and disposal of live bait.

Whether or not a lake is listed as infested, Minnesota law requires water recreationists to:

  • Clean watercraft of all aquatic plants and prohibited invasive species.
  • Drain all water by removing drain plugs and keeping them out during transport.
  • Dispose of unwanted bait in the trash.
  • Dry docks, lifts, swim rafts and other equipment for at least 21 days before placing equipment into another water body.
Report new occurrences of rudd to the DNR immediately by contacting your DNR Invasive Species Specialist or log in and submit a report through EDDMapS.
Control Methods
There is no effective population control for rudd in natural water bodies at this time, therefore, efforts are focused on prevention strategies.
Resources

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