Common carp (Cyprinus carpio)

Synonyms: Cyprinus carpio carpio

Common Names: European carp, German carp, koi, mirror carp, leather carp

Description:

Common carp (Cyprinus carpio) is a large bottom-feeding fish in the minnow family, native to Asia and parts of Europe and brought to North America in the 1870s as a food and sport fish [1][3]. It is now one of the most widespread fish on the continent, established in nearly every U.S. state [1]. MISIN tracks it because, as it roots in the bottom mud to feed, it muddies the water and uproots aquatic plants ? degrading shallow lakes and wetlands for native fish, plants, and waterfowl [2][3].

Identification:

Common carp is a large, heavy-bodied fish ? usually 16 to 18 inches long but able to reach about 4 feet and weigh tens of pounds ? with a deep body that arches up to the dorsal fin [1][3]. It is brassy yellow to golden-brown or olive on the sides and pale below, with large scales that each have a dark base, and the tail and anal fins often show some red [3]. The surest clues are at the mouth and fins: it has two pairs of fleshy whiskers (barbels) around the mouth (the rear pair larger), and a stout, saw-toothed spine at the front of both the long dorsal fin and the anal fin [3].

It is most noticeable in late spring and early summer, when carp splash and thrash in the shallows to spawn, and wherever the water is stirred muddy and aquatic plants are uprooted around their feeding areas [2][3]. Some domesticated forms look different ? brightly colored koi, or "mirror" and "leather" carp with few or no scales ? but all share the barbels and spined fins [1].

At-a-glance cues:

1. Large, deep, heavy body, brassy gold to olive with large dark-based scales [3]
2. Two pairs of barbels (whiskers) around the mouth ? the key feature [3]
3. A stout, saw-toothed spine at the front of the dorsal and anal fins [3]
4. Found in warm, shallow, vegetated water, often where the bottom is stirred muddy [1][3]

Habitat:

Common carp live in warm, shallow, quiet, well-vegetated fresh water ? the pools of small to large rivers, plus lakes, ponds, and wetlands [1]. They are tough and adaptable, tolerating low oxygen, murky water, and pollution better than most native fish, which helps them dominate disturbed and nutrient-rich waters [2][3].

The species is native to Asia and parts of Europe (the Caspian and Black Sea region), where it has been raised in ponds for thousands of years [1][2]. It was brought to North America from Germany by the U.S. Fish Commission in the 1870s and stocked widely as food and sport, and it is now established across southern Canada and nearly all of the United States [1][3]. It is listed among the world's 100 worst invasive species [2].

Reproduction:

Common carp spread both on their own and with human help. They were stocked deliberately for decades, and they still spread when people release ornamental koi or pond carp into the wild, dump unused live bait, or move fish and water between water bodies [1][2]. Once in a connected waterway, they can swim into new lakes and rivers and build large populations quickly [1].

Carp are prolific breeders. They spawn in spring and early summer once the water warms (to about 64 ?F / 18 ?C), scattering huge numbers of sticky eggs over plants and flooded shallows ? a single large female can release hundreds of thousands of eggs ? and they mature in about two to three years [2]. Because a few fish can seed an enormous population, the most important step for the public is preventing their spread: never release koi or bait, and never move live fish or water (see Management) [1][2].

Impact and Damage:

Common carp is not a danger to people, but it is one of the most damaging aquatic invaders, especially in shallow lakes and wetlands [2]. As carp root through the bottom mud to feed, they uproot and destroy aquatic plants and stir up sediment, clouding the water [2][3]. That murky water blocks the sunlight other plants need and makes it harder for sight-feeding native fish to find food, so plant beds and clear-water habitats decline [3].

Their feeding also stirs phosphorus out of the sediment into the water, which can fuel algae blooms and further cloud the water ? a cycle that can flip a clear, plant-rich lake into a murky, algae-dominated one [2]. These changes degrade habitat and food for native fish and for waterfowl that depend on aquatic plants, and they reduce a lake's recreational and water-quality value [2][3]. Because carp can reshape whole shallow-water systems this way, they are considered an ecosystem "engineer" with outsized effects [2].

Similar species:

A few large fish can be mistaken for common carp; the barbels and spined fins are the best check.

Goldfish (Carassius auratus) is a close relative and also introduced, but it has no barbels around the mouth, unlike common carp's two pairs ? and the two can even hybridize, making intermediate fish.

Grass carp (Ctenopharyngodon idella) is another introduced carp, but it has a more torpedo-shaped body, no barbels, and lacks the saw-toothed dorsal spine of common carp.

Suckers and buffalo (family Catostomidae) are large native bottom-feeders of similar size and color, but they have no barbels and a downturned, fleshy sucker mouth, and they lack the stout serrated fin spine of common carp.

Monitoring and rapid response:

Signs to watch for:

1. Large, deep-bodied, brassy-gold fish with barbels at the mouth and a serrated spine at the front of the dorsal fin [3]
2. Muddy, stirred-up water and uprooted aquatic plants around feeding areas [2][3]
3. Carp splashing and thrashing in the shallows while spawning in late spring and early summer [3]

What you can do:

1. Never release ornamental koi or pond carp into any lake, pond, or stream ? released ornamental carp can establish wild populations [1].
2. Never dump live bait, and never move live fish or water from one water body to another; Clean, Drain, and Dry boats and gear between waters [1].
3. Because common carp is already widespread and established, a single homeowner usually cannot remove it from a water body ? the most useful action is preventing further spread and reporting new occurrences (below) [1].
4. Lake associations and natural area crews concerned about carp in a specific lake should work with their state fisheries or aquatic invasive species program, which can assess options such as barriers, water-level management, and targeted removal at the right scale [1][3].

When to call a professional:

1. A carp problem in a lake, pond, or wetland you manage ? contact your state fisheries or aquatic invasive species program or a lake-management professional, since effective carp control is a coordinated, water-body-scale effort [1][3].
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. U.S. Geological Survey, Nonindigenous Aquatic Species Database. Cyprinus carpio Linnaeus, 1758 ? Common Carp (Species Profile). nas.er.usgs.gov
2. IUCN SSC Invasive Species Specialist Group, Global Invasive Species Database. Cyprinus carpio. iucngisd.org
3. Minnesota Department of Natural Resources. Common Carp (Cyprinus carpio). dnr.state.mn.us

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