Photographer: Miroslav Fiala Source: EOL.org Copyright: (CC BY-NC 3.0)
The crucian carp (Carassius carassius) is gold, deep bodied, laterally compressed, with spine-like anal fins, and no barbels on the mouth. There is a slender or shallow bodied morph that has been reported occasionally. An average mature crucian carp will weigh 5 kg and have a length of 50 cm. The crucian carp looks similar to the common goldfish (Carassius auratus), but can be differentiated by a slightly emarginate caudal fin and a slightly convex dorsal fin. The common goldfish has a deeply emarginate caudal fin and a straight dorsal fin.
Establishment of the crucian carp has not been reported in the United States, so the impact of invasion can only be speculated based on observations of related invasive carp. Belonging to the same family, Cyprinidae, the imported grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) are known for their aggressive foraging behavior and ability to out-compete native fish species. The silver carp is also known for its jumping ability with accounts of the fish jumping into boats and injuring people or damaging equipment.
The crucian carp is often described as having a hearty heart rate documented in cases where the fish can survive in anoxic waters with low temperatures near 0o C. Research indicates that the rapid heart rate allows the crucian carp to survive with minimal oxygen in the water by continuing to pump ethanol out of the body that is created from breathing and specific to the crucian carp. Anaerobic respiration and suspended animation are believed to allow the crucian carp to survive in temperatures near freezing with minimal food resources available.
Habitat: Adult crucian carp can be found in permanent fresh bodies of water such as lakes, but will often travel up stream when possible to spawn and lay eggs. Rice paddies and drainage ditches are commonly used for laying eggs in Japan indicating a preference for shallow water during egg deposition.
Crucian carp and other members of the family Cyprinidae are cultivated in aquaculture in China as a vital food source. Many of these invasive carp species present in the U.S., including the Crucian carp, were imported as food sources or as a control agent in aquatic environments. The crucian carp is believed to have been imported with other invasive carps such as the grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), and bighead carp (Hypophthalmichthys nobilis), but there are currently no reports of uncontrolled populations occurring in the U.S. Movement and farming of Asian carp has been banned in several states to help control the spread of these highly invasive fish.
Europe and Siberia
U.S. Present: In the 1900's there were reports of crucian carp living in lagoons and parks in Chicago, IL. However, further reports indicate that this population has died out. There have been other reports in the 90's of the crucian carp hybridizing with its congener the common goldfish (Carassius auratus) in Texas, but these accounts have not been verified. In January 15, 2014 there was one recorded sighting in Cook County, Illinois.
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