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Figure 15. Crucian Carp, UF 30247, 101 millimeter SL, from Yeosu, South Korea.
The Crucian Carp (fig. 15) is medium-sized fish, usually <50 cm TL and 1.8 kg (Wheeler, 1978). Maximum size is about 64 cm TL (IGFA, 2001) and 5 kg (Berg, 1964). Typically, individuals are deepbodied and laterally compressed (fig. 16); however, a slender “shallow-bodied” variety also exists (fig. 17). The dorsal fin has iii-iv (14-21) rays and a stout, spinelike ray precedes the branched rays. The anal fin has ii-iii (5-8) rays. The mouth is terminal and oblique, and the peritoneum is pale. The lateral line is complete, with 28-37 relatively large scales. The pharyngeal teeth are in one row (0,4-4,0; fig. 18). Gill rakers on the first arch count 22-33. The body is golden copper, darker dorsally, with reddish fins. Sexual dimorphism is not pronounced (Szczerbowski and Szczerbowski, 2001). Meristics are given in appendix B.
The long dorsal fin of the Crucian Carp, with a strong, serrated spine-like ray followed by 15 or more branched rays, distinguishes it from most native North American cyprinids, which usually lack the spine-like ray and typically have fewer than 11 branched dorsal rays.
Of the foreign nonindigenous cyprinids, the Crucian Carp most closely resembles the Goldfish and Common Carp. Crucian Carp is distinguished from Goldfish by its slightly convex dorsal-fin margin and slightly emarginate caudal fin; juvenile and young adult Crucian Carp have a black spot at the base of the caudal fin. The Goldfish has a straight or slightly concave dorsal-fin margin, a deeply emarginate caudal fin, and lacks the spot at the base of the caudal fin. The typical form of the Crucian Carp is slightly deeper bodied than Goldfish. Denticles on the posterior margin of the spine-like dorsal ray are smaller and more numerous in Crucian Carp (28-29) than in Goldfish (10-11). Crucian Carp lacks barbels, which distinguishes it from Common Carp.
Figure 18. Pharyngeal teeth (0,4-4,0) of Crucian
Due to ecological factors, such as predatory pressure, Crucian Carp varieties can be either deep bodied or shallow bodied (Holopainen and others, 1997). The typical deep-body form is strongly arched dorsally (fig. 16), whereas the shallow-body form, referred to as humilis (Banarescu, 1964), is more fusiform (fig. 17). Many of the systematic problems mentioned in our account on Goldfish also apply to Crucian Carp.
The Crucian Carp regularly hybridizes with Common Carp (Banarescu, 1964; Berg, 1964; Lin and Peter, 1991). An illustration of a hybrid Crucian Carp X Common Carp originally published by Antipa (1909), appears in Banarescu (1964, p. 504). Meristics of Crucian Carp X Common Carp hybrids are given in appendix B. The Crucian Carp also hybridizes with Goldfish (Szczerbowski, 2001). Attempts to crossbreed Crucian Carp with other cyprinids (including Grass Carp, Rudd, and Tench) produced hybrids with high levels of mortality (Kasama and Kobayasi, 1989, 1990; and Riabov, 1979, in Szczerbowski and Szczerbowski, 2001).
Age at sexual maturity varies with environmental conditions, with individuals in warmer regions generally maturing faster than those in colder ones. Most Crucian Carp mature between 2-5 years of age, with males generally maturing a year earlier than females. The species is a batch spawner, releasing adhesive eggs over vegetation when water temperatures rise above 18 °C (Aho and Holopainen, 2000; Szczerbowski and Szczerbowski, 2001). The eggs are spherical, yellow-orange, and are about 1.5 mm in diameter (Laurila and Holopainen, 1990). The eggs remain attached to vegetation until they hatch in about 4 days at 20 °C (Laurila and others, 1987). The larvae possess an adhesive gland on the forehead, which allows them to adhere to submerged vegetation until the yolk sac is absorbed about 10 days after hatching (Szczerbowski and Szczerbowski, 2001). Egg, larval, and juvenile development were described in Laurila and Holopainen (1990).
The Crucian Carp typically grows to about 50 cm TL and 1.8 kg (Wheeler, 1978); however, individuals may attain sizes of up to 64 cm TL (IGFA, 2001) and 5 kg (Berg, 1964). The maximum lifespan of wild Crucian Carp is about 10 years (Szczerbowski and Szczerbowski, 2001). Habitat generally includes shallow, slow-flowing parts of rivers, lakes, and ponds with abundant submerged aquatic vegetation. The species is capable of inhabiting temporary ponds by burying into mud as water levels decrease (sometimes for several weeks) until normal water levels become available again (Rybkin, 1958, in Szczerbowski and Szczerbowski, 2001). Predation may significantly alter densities and size-structures of populations. A Swedish study showed that lakes containing predators often contained high densities of shallow-bodied Crucian Carp, whereas lakes without predators contained larger, deep-bodied individuals (Bronmark and others, 1995; Holopainen and others, 1997). The Crucian Carp is a remarkably hardy fish. Historical accounts report the species can live for hours out of the water, and can survive packaging and transport in snow or damp leaves (Seeley, 1886). Like Goldfish, the Crucian Carp is tolerant of low-oxygen conditions and high turbidity. Survival has been documented at water temperatures below 0 °C, and individuals may even survive for a few days with a frozen integument (Szczerbowski and Szczerbowski, 2001). The preferred temperature for Crucian Carp was reported as 27 °C and the upper lethal temperature was 38.5 °C (Hellawell, 1986). The ability to use anaerobic metabolism allows Crucian Carp to survive for several months in anoxic water at low temperatures, for example, in lakes frozen over with ice (Holopainen and Hyvarinen, 1984; Piironen and Holopainen, 1986). In their native range, feeding may stop for several months as the fish rest in a state of “suspended animation” during winter months when ponds become anoxic and covered with ice (Zhadin and Gerd, 1963; Penttinen and Holopainen, 1992). In addition to depressing cellular energy demands, the Crucian Carp was reported to respond to anoxia by decreasing its swimming activity by about 50 percent of that displayed during normoxia (Nilsson and others, 1993). Crucian Carp can survive indefinitely over a pH range of 4.0-10.5 (Hellawell, 1986). There is some evidence that the species is tolerant to low levels of salinity. For example, in parts of the former Soviet Union, the Crucian Carp inhabits brackish lakes of the steppe with salinities to 16 ppt, and spawns in the saline Volga River Delta (Zhadin and Gerd, 1963).
The Crucian Carp is omnivorous (Prejs, 1973), and its diet varies seasonally (Penttinen and Holopainen, 1992). Diet studies report a predominance of cladocerans as well as trichopterans, rotifers, ostracods, copepods, chironomids, ephemeropterans, nematodes, algae, detritus, and plant matter (Prejs, 1973; Penttinen and Holopainen, 1992).
The Crucian Carp is native to Europe and Asia. For details of the native range, refer to Szczerbowski and Szczerbowski (2001).
Over the past two centuries, there have been a few scattered reports of the occurrence of Crucian Carp in the U.S. (possibly involving hybrids with either Goldfish or Common Carp). Meek and Hildebrand (1910) reported Crucian Carp thriving in the lagoons and parks of Chicago. However, a more recent work on Illinois fishes (Smith, 1979) suggested this population disappeared long ago. There are no recent reports of established populations of Crucian Carp in the U.S. An earlier report that the species had been introduced into Texas (see Fuller and others, 1999) is now considered unlikely. Robert Howells (Texas Parks and Wildlife Department, personal commun, 2004) believes that the species was never introduced into Texas and that earlier reports were probably based on Goldfish. Although the status of previous introductions is uncertain, fish farmers in Arkansas have recently been contacted by commercial fish markets about the possibility of culturing the species for the live-food fish trade in the U.S. Future importation of Crucian Carp may lead to its introduction and possible establishment. Consequently, its introduction and status remain uncertain. For additional details, refer to Fuller and others (1999).
Plate 3. Distribution of Crucian Carp in the United States. See Methods for details regarding
Crucian Carp from Denmark. Upper photo from Vaerlose, Denmark; lower photo from Danmarks Akvarium
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