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Goldfish
Carassius auratus (Linnaeus 1758)

Figure 11. Goldfish, SIUC 22609, 122.5 millimeter SL, from Alexander County, Illinois.

Figure 11. Goldfish, SIUC 22609, 122.5 millimeter SL, from Alexander County, Illinois.

Description

       The Goldfish (fig. 11) is a robust, medium-sized cyprinid that generally reaches 15-20 cm TL and weighs 100-300 g (Szczerbowski, 2001). Maximum size is about 59 cm TL and 3 kg (IGFA, 2001). The lateral line is complete, typically with 26-33 scales (range 25-36). The mouth is terminal, slightly oblique, and lacks barbels. The dorsal fin is long with iii-iv (13-19) rays, and a stout, spine-like ray precedes the branched rays. The anal fin has ii-iii (5-6) rays. The caudal fin is deeply emarginate and the belly lacks a keel. Pharyngeal teeth are in one row (0,4-4,0) and are somewhat molarlike, but narrow and smooth edged, without extensive grinding surfaces (fig. 12). Gill rakers on the first arch number 37-53. The peritoneum is blackish. Sexual dimorphism is not pronounced (Dombrovski, 1964, in Szczerbowski, 2001). Wild Goldfish are typically olive-green, gray, or silver; ornamental forms exhibit a range of colors (see section on variation, below). Breeding males may develop small nuptial tubercles on the operculum, dorsum, and pectoral fin rays (Coad, 2005). These structures are white and small; often giving the false impression the fish is infected with the disease “ich.” Meristics for Goldfish are given in appendix B.

Figure 12. Pharyngeal teeth (0,4-4,0) of Goldfish, SIUC 22609, 122.5 millimeter SL, from Alexander County, Illinois. (Also see fig. 3)

Figure 12. Pharyngeal teeth (0,4-4,0) of Goldfish,
SIUC 22609, 122.5 millimeter SL, from Alexander
County, Illinois. (Also see fig. 3.)

Similar Species

       The long dorsal fin of the Goldfish, with a strong, serrated, spinous ray followed by 13 or more branched rays, distinguishes it from most native North American cyprinids, which typically have fewer than 11 rays and usually lack the spine-like ray. Goldfish superficially resemble suckers (family Catostomidae), particularly buffalos (genus Ictiobus) and carpsuckers (genus Carpiodes); however, suckers do not have spine-like rays in the dorsal and anal fins.

       Among foreign nonindigenous cyprinids, the Goldfish most closely resembles the Common Carp and Crucian Carp. Goldfish lacks barbels, which readily distinguishes it from the Common Carp (that has two pairs of barbels). Differences between larval Goldfish and Common Carp were illustrated by Gerlach (1983). Goldfish is distinguished from Crucian Carp by its straight or slightly concave dorsal-fin margin, blackish peritoneum, a deeply emarginate caudal fin, and the absence of a spot at the base of the caudal fin. Crucian Carp has a slightly convex dorsal-fin margin, light peritoneum, a slightly emarginate caudal fin, and a blackish spot at the base of the caudal fin that is more apparent in juveniles. The posterior margin of the large, spine-like dorsal ray has 10-11 large denticles in Goldfish versus 28-29 small denticles in Crucian Carp. Additionally, the Goldfish is typically slightly less deep-bodied than Crucian Carp. The pharyngeal teeth of Goldfish and Crucian Carp are nearly identical.

Variation

       The Goldfish exhibits a wide range of sizes, shapes, and colors of the body and fins. Much of the variation is the result of artificial breeding, and some is due to natural causes associated with age or growth changes. For example, as observed in many species, there is an increase in the number of gill rakers on the first arch with growth (Dombrovski, 1964, in Szczerbowski, 2001). Artificial selection from a long history of culture has also intensified variability in body shape and color.

       The Goldfish was probably the first cultured fish; its domestication began thousands of years ago in China (Balon, 1995). The classic cultured form, known to aquarists as “Fancy Goldfish” (fig. 13), is reddish golden with yellow fins; however, artificial selection by breeders has produced a number of varieties for the pet trade (for example, Comets, Veiltails, and Shubunkins). Several varieties have been produced with body colors of red, white, gold, black, and combinations of these. Some varieties have been produced that lack a dorsal fin, others have greatly elongated fins (especially the caudal) or multiple fins (especially the caudal and anal), and some have telescoping eyes (for example, Penzes and Tolg, 1983). Some cultivars may be variegated and some have no scales. These colorful forms are in contrast to the wild type, which is generally olivaceous, varying in color from gray-green, green-brown or gray (fig. 14). Wild populations of Goldfish often revert to olive-green coloration, presumably because the brightly colored ones are eliminated by bird and fish predators (Moyle, 2002; Wydoski and Whitney, 2003).

       In treating Carassius auratus, recent authorities often recognize two subspecies: Carassius auratus gibelio (Bloch, 1783), commonly known as Prussian, Silver Crucian, European Goldfish, or Gibel Carp; and Carassius auratus auratus, generally referred to as Goldfish. However, the taxonomy of the genus Carassius is not fully understood due to a combination of confounding factors, including wide morphological variation within purported species, overlap in morphology between species (and also between subspecies), widespread introductions, high frequency of hybridization, and other genetic complexities such as triploidy (Fuller and others, 1999; Iguchi and others, 2003). In addition to other nomenclatural disagreements, some authors recognize gibelio as a separate species rather than a subspecies under C. auratus. According to Coad (2005), elongate specimens (morpha humilis) occur where fish density is high, and deep-bodied specimens (morpha vovki) occur where fish density is low; however, the author noted that the names humilis and vovki have no taxonomic significance. To add to the confusion, Banarescu (1964) described the same type variation in body shape for Carassius carassius (see section on variation under account on the Crucia Carp). Whether Carassius auratus is a highly variable species as opposed to a complex of multiple species may only be resolved by further investigation combining morphological and molecular analyses.

       The Goldfish naturally hybridizes with Common Carp (see appendix B for meristics) and Crucian Carp, giving rise to individuals that are intermediate in morphology between the two parent species (Smith, 1979; Szczerbowski, 2001). A natural intergeneric hybrid of Barbus sharpeyi and Carassius auratus was recently described from a small lake in Iran (Al-Mukhtar and Al-Hassan, 1999, cited by Coad, 2005). However, there are no known hybrids with North American cyprinids. For a listing of other known hybrids between Goldfish and various Old World species, refer to Schwartz (1972, 1981).

Figure 13. Cultured (fancy) form of Goldfish; 110 millimeter SL adult purchased from pet store. (Photo copyright  Richard T. Bryant.)

Figure 13. Cultured (fancy) form of Goldfish; 110 millimeter SL adult purchased
from pet store. (Photo copyright Richard T. Bryant.)

Figure 14. Wild (olivaceous) form of Goldfish; 170 millimeter SL adult, from Douglas Reservoir, Tennessee. (Photo copyright  Richard T. Bryant.)

Figure 14. Wild (olivaceous) form of Goldfish; 170 millimeter SL adult,
from Douglas Reservoir, Tennessee. (Photo copyright  Richard T. Bryant.)

Reproduction

       Sexual maturity is reached at 1-2 years of age, and reproduction occurs annually for about 6-7 years (Robison and Buchanan, 1988). Females scatter their adhesive eggs over vegetation, roots, or other fixed objects (Hensley and Courtenay, 1980; Robison and Buchanan, 1988). The Goldfish is a batch spawner, reproducing in the spring and summer when temperatures are above 16 °C (Robison and Buchanan, 1988). Eggs take 3-7 days to hatch, depending on temperature (Wheeler, 1969; Moyle, 2002; Boschung and Mayden, 2004). Egg and larval development were described in Nakamura (1969) and Jones and others (1978). Exceptional camera lucida illustrations of egg and larval development were presented in Battle (1940).

Ecology

       Goldfish may reach 59 cm TL and up to 3.0 kg (IGFA, 2001); however, they generally reach only 15-20 cm TL and weigh 100-300 g (Szczerbowski, 2001). Lifespan is typically 6-7 years, but has been reported as long as 30 years (Essing, 1898, in Carlander, 1969).

       Typical habitat includes the quiet backwaters of streams and pools, especially those with submerged aquatic vegetation (Hensley and Courtenay, 1980; Trautman, 1981; Robison and Buchanan, 1988). The Goldfish is tolerant of high levels of turbidity (Wallen, 1951), temperature fluctuations (reviewed by Spotila and others, 1979), and low levels of dissolved oxygen (Zhadin and Gerd, 1963; Walker and Johansen, 1977). Laboratory results reported pH tolerance levels between 4.5-10.5, and a preference for pH levels between 5.5-7.0 (Szczerbowski, 2001). Although laboratory tests suggested that eggs and fry are not particularly salinity tolerant (Murai and Andrews, 1977), the Goldfish is reported to live in salt lakes on the coast of the Black Sea and to inhabit the floodplain of the Ob delta in Russia (Zhadin and Gerd, 1963). The Goldfish has been captured in waters with salinities as high as 17 parts per thousand (ppt) (Schwartz, 1964), although studies have shown an inability to withstand long exposures exceeding 15 ppt (Lockley, 1957). Adults thrive equally well in salinities between 0-6 ppt (Canagaratnam, 1959), and can survive water temperatures between 0-41 °C (Carlander, 1969; Moyle, 2002). Additionally, the species is more tolerant of aquatic pollution than most native North American fishes (Robison and Buchanan, 1988).

       The omnivorous, diet includes planktonic crustaceans, phytoplankton, insect larvae, fish eggs and fry, benthic vegetation, and detritus (Scott and Crossman, 1973; Hensley and Courtenay, 1980; Robison & Buchanan, 1988; Moyle, 2002). Foraging Goldfish may create high levels of turbidity, which can result in the decline of aquatic vegetation (Richardson and others, 1995).

Native Distribution

       The Goldfish is native to Eastern and Central Asia, including China, Russia, Korea, and possibly Japan and Taiwan (Wheeler, 1978; Szczerbowski, 2001). It may also be native to parts of eastern Europe (Raicu and others, 1981); however, widespread transfer over several centuries has obscured the natural distribution.

U.S. Introductions

       The Goldfish is thought to be the first foreign fish species introduced to North America (De Kay 1842; Courtenay and others, 1984; Fuller and others, 1999). The first recorded releases in the U.S. probably occurred during the late 1600s (De Kay, 1842; Courtenay & Stauffer, 1990), and the species is now reported in all states except Alaska (Fuller and others, 1999). The Goldfish is raised for the aquarium trade (as both an ornamental and live food), as bait for anglers, and as forage in fish hatcheries. Bait dealers in coastal regions along the Gulf of Mexico sometimes sell Goldfish under the names “Black Saltys” or “Black Salties.” Although not typically eaten by humans in the U.S., it is a valued food fish in China. Escapes from aquaculture facilities and deliberate releases have resulted in the establishment of localized populations across much of the U.S. The exact distribution is difficult to ascertain, as introductions continue intermittently throughout much of the country.

Carassius auratus
Goldfish
Plate 2. Distribution of Goldfish in the United States. - click to enlarge

Plate 2. Distribution of Goldfish in the United States. See Methods for details regarding data used to
create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

Angler with Goldfish captured in canal in Beijing, Peoples Republic of China, 2004. (Photo by Leo G. Nico.)

Angler with Goldfish captured in canal in Beijing,
Peoples Republic of China, 2004. (Photo by Leo G. Nico.)


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