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<br />
<br />M"T
<br />
<br />Figure 18. Pharyngeal teeth (0,4-4,0) of Crucian
<br />Carp, UF 30247,101 millimeter SL, from Yeosu,
<br />South Korea.
<br />
<br />Variation
<br />
<br />Due to ecological factors, such as predatory
<br />pressure, Crucian Carp varieties can be either deep
<br />bodied or shallow bodied (Holopainen and others, 1997).
<br />The typical deep-body form is strongly arched dorsally
<br />(fig. 16), whereas the shallow-body form, referred to as
<br />humi/is (Banarescu, 1964), is more fusiform (fig. 17).
<br />Many of the systematic problems mentioned in our
<br />account on Goldfish also apply to Crucian Carp.
<br />The Crucian Carp regularly hybridizes with
<br />Common Carp (Banarescu, 1964; Berg, 1964; Lin
<br />and Peter, 1991). An illustration of a hybrid Crucian
<br />Carp X Common Carp originally published by Antipa
<br />(1909), appears in Banarescu (1964, p. 504). Meristics
<br />of Crucian Carp X Common Carp hybrids are given
<br />in appendix B. The Crucian Carp also hybridizes with
<br />Goldfish (Szczerbowski, 200 I). Attempts to crossbreed
<br />Crucian Carp with other cyprinids (including Grass
<br />Carp, Rudd, and Tench) produced hybrids with high
<br />levels of mortality (Kasama and Kobayasi, 1989, 1990;
<br />and Riabov, 1979, in Szczerbowski and Szczerbowski,
<br />2001).
<br />
<br />Reproduction
<br />
<br />Age at sexual maturity varies with environmental
<br />conditions, with individuals in warmer regions generally
<br />maturing faster than those in colder ones. Most Crucian
<br />Carp mature between 2-5 years of age, with males gener-
<br />ally maturing a year earlier than females. The species is
<br />a batch spawner, releasing adhesive eggs over vegetation
<br />when water temperatures rise above 18 oC (Aho and
<br />
<br />Crucian Carp 27
<br />
<br />Holopainen, 2000; Szczerbowski and Szczerbowski,
<br />2001). The eggs are spherical, yellow-orange, and are
<br />about 1.5 mm in diameter (Laurila and Holopainen,
<br />1990). The eggs remain attached to vegetation until
<br />they hatch in about 4 days at 20 oC (Laurila and others,
<br />1987). The larvae possess an adhesive gland on the
<br />forehead, which allows them to adhere to submerged
<br />vegetation until the yolk sac is absorbed about 10 days
<br />after hatching (Szczerbowski and Szczerbowski, 200 I).
<br />Egg, larval, and juvenile development were described in
<br />Laurila and Holopainen (1990).
<br />
<br />Ecology
<br />
<br />The Crucian Carp typically grows to about 50 em
<br />TL and 1.8 kg (Wheeler, 1978); however, individu-
<br />als may attain sizes of up to 64 cm TL (lGFA, 2001)
<br />and 5 kg (Berg, 1964). The maximum lifespan of wild
<br />Crucian Carp is about 10 years (Szczerbowski and
<br />Szczerbowski, 200 I). Habitat generally includes shal-
<br />low, slow-flowing parts of rivers, lakes, and ponds with
<br />abundant submerged aquatic vegetation. The species is
<br />capable of inhabiting temporary ponds by burying into
<br />mud as water levels decrease (sometimes for several
<br />weeks) until normal water levels become available again
<br />(Rybkin, 1958, in Szczerbowski and Szczerbowski,
<br />200 I). Predation may significantly alter densities and
<br />size-structures of populations. A Swedish study showed
<br />that lakes containing predators often contained high
<br />densities of shallow-bodied Crucian Carp, whereas
<br />lakes without predators contained larger, deep-bodied
<br />individuals (Bronmark and others, 1995; Holopainen and
<br />others, 1997). The Crucian Carp is a remarkably hardy
<br />fish. Historical accounts report the species can live for
<br />hours out of the water, and can survive packaging and
<br />transport in snow or damp leaves (Seeley, 1886). Like
<br />Goldfish, the Crucian Carp is tolerant of low-oxygen
<br />conditions and high turbidity. Survival has been docu-
<br />mented at water temperatures below 0 oC, and indi-
<br />viduals may even survive for a few days with a frozen
<br />integument (Szczerbowski and Szczerbowski, 200 I).
<br />The preferred temperature for Crucian Carp was reported
<br />as 27 oC and the upper lethal temperature was 38.5 oC
<br />(Hellawell, 1986). The ability to use anaerobic metabo-
<br />lism allows Crucian Carp to survive for several months
<br />in anoxic water at low temperatures, for example, in
<br />lakes frozen over with ice (Holopainen and Hyvarinen,
<br />1984; Piironen and Holopainen, 1986). In their native
<br />range, feeding may stop for several months as the fish
<br />rest in a state of "suspended animation" during winter
<br />months when ponds become anoxic and covered with
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