Carassius auratus

Invasion History

First Non-native North American Tidal Record: 1839
First Non-native West Coast Tidal Record: 1933
First Non-native East/Gulf Coast Tidal Record: 1839

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General Invasion History:

Goldfish (Carassius auratus) are native to China, Korea, and Eurasia from the Lena to the Amur Rivers; and possibly were introduced in ancient times to Japan, Hainan, and Taiwan (Courtenay et al. 1984). They have been released many times, deliberately and accidentally, from the beginning of importation and culture in North America. They have been collected in the wild in all US states except Alaska (Fuller et al. 1999), and on all continents except Antarctica (Lever 1996). Goldfish were brought to North America in the 1600s and were established in waters around New York and Boston by the 19th century (Storer 1839, cited by Hartel 2002; De Kay 1842). They were spread by the commercial pet trade. They were raised by the United States Fish Commission (USFC) in Washington and distributed to individuals in at least 37 states between 1878 and 1893 (Smiley 1884a; Bean 1893). Established populations are found in many rivers flowing past major cities (Courtenay et al. 1984). This fish has been introduced to 49 states, but establishment is uncertain in some southern states (Fuller et al. 1999). Many wild populations are sporadic, but others are well-established (Courtenay et al. 1984).

North American Invasion History:

Invasion History on the West Coast:

Goldfish have been widely distributed in western North America, but the only estuarine populations of which we are aware, are in the Columbia River and the San Francisco Estuary (Cohen and Carlton 1995; Sytsma et al. 2004; USGS Nonindigenous Aquatic Species Program 2018). Commercial rearing Goldfish in the West started in the late 19th century. Goldfish were distributed to private individuals in California by the USFC as early 1882-1884 to encourage fish-farming, but it is not known if any of these fish were released to the wild (Dill and Cordone 1997).

Columbia River- The first sighting of Goldfish in the wild was from a bridge over the Willamette River, in Portland, Oregon in 1933 (Lampman 1946). Goldfish were later found further down river in Kalama, WA and near the mouth of the river in Astoria, OR (Chapman 1942). Most recent records are from the Portland area (Farr and Ward 1993; Sytsma et al. 2004)

San Francisco Estuary- Goldfish were probably widely kept and reared in California in the 20th century, but the earliest record from the Sacramento-San Joaquin Delta is 1963. Most catches occurred in upstream portions of the Delta (Herbold and Moyle 1989, cited by Cohen and Carlton 1995; Brown and Michniuk 2007), but they were also caught in Suisun Marsh (Matern et al. 2002; Feyrer and Healey 2003). They appear to have declined in abundance in recent decades, comprising ~3% catches reported by Herbold and Moyle (1989), and less than 1% on later lists (Matern et al. 2002; Feyrer and Healey 2003; Brown and Michniuk 2007).

Invasion History on the East Coast:

Goldfish were introduced to eastern North America in the 1600s and established around major cities by the mid-19th century. They were established in the Charles River waters around Boston by 1839 (Storer 1839, cited by Hartel et al. 2002), the Connecticut River in Hartford by 1844 (Whitworth 1968), the Hudson River in New York (de Kay 1842), the Delaware River in Philadelphia and the Potomac River in Washington by 1876-1879 (Uhler and Lugger 1876; Cope 1879). In estuaries Goldfish are most common in tidal fresh waters, but have been collected at salinities as high as 17 PSU (Schwartz 1965). In the Hudson River, they are most common in the upper and middle estuary (Mills et al. 1997; Daniels et al. 2005), but with some occasionally stray into New York Harbor (Briggs and Waldman 2002). The population in the Hudson River went through great fluctuations – Goldfish were abundant until 1979-1980, then declined due to an epidemic of furunculosis, but dramatically recovered by 2002 (Daniels et al. 2005). In the Delaware estuary Goldfish range from Trenton, New Jersey (the head of tide) to the brackish mouth of the Chesapeake and Delaware Canal in Chesapeake City, Maryland (Horwitz 1986; Weisberg et al. 2005). In the mainstem of the Chesapeake Bay, Goldfish range from the Conowingo Dam on the Susquehanna River, at the head of the Bay to the brackish waters of the Rhode River (McKeown 1984; Rob Aguilar, personal communication 2012). On the Potomac, they similarly range from the head of tide to the brackish Wicomico River (Lippson et al. 1979; Killgore et al. 1989; Starnes et al 2011). In Virginia, the only self-sustaining population may be in the Potomac (Jenkins and Burkhead 1993).

Records for estuarine waters south of Chesapeake Bay are rare, possibly because of higher summer temperatures. Isolated captures have been reported from the lower Altamaha River, Georgia (2018), the St. John River in Florida (1974), Galveston Bay, Texas (1990), and the lower Rio Grande (Poss 1990; Edwards and Contrera Balderas 1991; USGS Nonindigenous Aquatic Species Program 2018).

The early history of the Goldfish's invasion of the Great Lakes is not well-documented. There were probably releases of pet fish before 1878, the first documented transfers to the region began with United States Fish Commission (USFC)'s distributions of Goldfish to private individuals probably to encourage fish-farming (Emery 1985; Mills et al. 1993). The first lake-specific USGS records for Goldfish are 1925 for Lake Erie, 1957 for Lake Michigan, and 1964 for Lake Ontario (USGS Nonindigenous Aquatic Species Program 2018). Goldfish are most abundant in Lake Erie, which is warmer and shallower (Emery 1985). The only Lake Superior record is from a pond draining into the deep, cold lake (USGS Nonindigenous Aquatic Species Program 2018).

Invasion History in Hawaii:

Goldfish were introduced to the Hawaiian Islands before 1900 and occur in reservoirs on all the main islands (Brock 1960; Maciolek 1984).

Invasion History Elsewhere in the World:

Goldfish have been introduced to at least 62 countries (Food and Agricultural Organization 2018). Documented introductions to Europe occurred in 1611 in Portugal and 1665 in England, and were widely introduced as pets in Western Europe in the 18th century. Introductions to South Africa, South America, and Australia occurred in the 19th century, but most of the established populations seem to have been in subtropical and temperate regions (Lever 1996). Many populations are probably in urban ponds and reservoirs (Lever 1996). We have not found records of Goldfish in the brackish European Baltic and Black Seas.

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Description

Goldfish (Carassius auratus) belong to Cyprinidae, the carp and minnow family. Fish of this family have a single dorsal fin, abdominal pelvic fins, a lateral line, and cycloid (circular) scales. They lack true spines in their fins, but a few, including Common Carp (Cyprinus carpio), and Goldfish, have secondary spine-like structures. They lack teeth in their mouths, but have 1-3 rows of pharyngeal teeth. Most fishes of this family have forked tails (Page and Burr 1991). Goldfish have a stout and robust body with an elevated back, and a short head, and a ventral mouth lacking barbels. There are 25-34 scales on the lateral line. The dorsal fin is long, with a stout, saw-toothed spine-like ray with 15-21 rays. The anal fin has six rays, the first ray is spine-like (Page and Burr 1991; Murdy et al. 1997; Moyle 2002; Schofield et al. 2005). Goldfish can reach a length of 410 mm, but are more typically 120-170 mm (Moyle 2002). One book calls Goldfish the 'poodle of the fish world', with morphology and color radically changed by centuries of human selection (Rohde et al. 1994). When released into a natural environment natural selection by predators rapidly reverts the population to the 'wild-type'. Wild Goldfish are usually gray-green above, with brassy sides and a white or yellow belly (Page and Burr 1991; Murdy et al. 1997; Moyle 2002).

The genus Carassius consists of five species native to Europe and Asia. Where their ranges overlap they hybridize with each other and the Common Carp (Cyprinus carpio) (Rylkova et al. 2013). Two of these carp, the Japanese Silver Carp (C. langsdorfii) and Prussian Carp (C. gibelio), have been introduced to western North America (Elgin et al. 2014; Halas et al. 2014). These carps and their hybrids can be confused with wild Goldfish, especially when young.

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Taxonomy

Ecology

General:

Goldfish (Carassius auratus) is a small-to-medium sized freshwater fish. The two sexes are not easily distinguished, though females are usually larger than males. The growth rate and size of this fish is strongly influenced by food and environment, including crowding in ponds and aquaria. For example, differences in growth rates were observed between populations in the Sacramento and San Joaquin Rivers (Moyle 2002). Age at maturity in culture can be as early as 8 months, but in wild populations, it occurs at 2-4 years (Jones et al. 1978; Wang 1986; Moyle 2002). Males in California usually mature in their second year (Moyle 2002). Fish can mature at sizes as small as 79 mm (Jones et al. 1978), but probably larger in the wild. A sample of females from the Sacramento River ranged from 121 to 169 mm (Moyle 2002). Fecundity varies greatly with size, from 2,000-400,000 (Jones et al. 1978). In wild populations in California, the average fecundity was 14,000 eggs per female (Moyle 2002). Spawning occurs over aquatic vegetation or tree-roots, with a male courting a female. The male fertilizes the eggs as they are scattered. The eggs adhere to vegetation, and hatch in three to ten days at 15 to 2.5 C (Jones et al. 1978; Wang 1986). The yolk-sac larvae are 3-5 mm at hatching, and remain near the bottom. They swim more as they develop; juveniles start forming schools at about 10 mm Wang 1986).

Goldfish, as indicated by their wide native and introduced geographical ranges, and their tolerance of captivity, are tolerant of a wide range of environmental conditions. They can survive winters in ice-covered ponds and can tolerate temperatures as high as 41 C (Carlander 1969; Jones et al. 1978). They have been collected at salinities as high as 17 PSU, although fish in experiments survived only 11-9 days at 15 PSU (Schofield et al. 2006). Egg and larval development can take place at 16-29.5 C and 0-8 PSU (Jones et al. 1978). In estuaries, Goldfish are most abundant in tidal freshwater, and often move upstream for spawning (Wang 1986; Murdy et al. 1997). They are tolerant of hypoxic conditions, and stagnant, polluted water (Jones et al. 1978; Moyle 2002). Goldfish prefer still or slowly flowing water, with heavy growth of vegetation. They are omnivorous, feeding on algae, vascular plants, detritus, and small benthic invertebrates (Murdy et al. 1997; Moyle 2002). Goldfish are relatively small and slow moving fish and are therefore vulnerable to fish and bird predators.

Food:

plants, algae, invertebrates

Consumers:

fishes, birds

Trophic Status:

Omnivore

Omni

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Habitats

General Habitat	Fresh (nontidal) Marsh	None
General Habitat	Grass Bed	None
General Habitat	Swamp	None
General Habitat	Nontidal Freshwater	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Unstructured Bottom	None
General Habitat	Canals	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Salinity Range	Mesohaline	5-18 PSU
Vertical Habitat	Nektonic	None

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Tolerances and Life History Parameters

None	4.5	None
Minimum Temperature (ºC)	0	Experimental- Carlander 1969; Jones et al. 1978
Maximum Temperature (ºC)	41	Experimental- Carlander 1969; Jones et al. 1978
Minimum Salinity (‰)	0	Field- Jones et al. 1978
Maximum Salinity (‰)	17	Field- Schwartz 1965. In experiments, "standard' goldfish purchased from dealers had a median survival time of 9 days after stepwise transfer to 15 ppt. A strain sold as a saltwater bait fish ('black salty') had a median survival time of 11 days at 15 ppt (Schofield et al. 2006)
Minimum pH	4.5	Szczerbowski, 2001, cited by Schofield et al. 2005
Maximum pH	10.5	Szczerbowski, 2001, cited by Schofield et al. 2005
Minimum Reproductive Temperature	16	Experimental- Jones et al. 1978
Maximum Reproductive Temperature	29.5	Experimental- Jones et al. 1978
Minimum Reproductive Salinity	0	Field- Jones et al. 1978
Maximum Reproductive Salinity	8	Experimental- Jones et al. 1978
Minimum Length (mm)	76	Size at maturity (Jones et al. 1978)
Maximum Length (mm)	400	Jones et al. 1978

General Impacts

Goldfish (Carassius auratus) are economically important as pets and are bred for their beauty. They are also used for bait and as feeder-fish for carnivorous pets, and as a forage fish gamefishes. When goldfish are released, they can develop dense populations in predator-free environments, which can have negative impacts by destroying aquatic plants and increasing turbidity (Richardson et al. 1995). In Australia, Goldfish reportedly feed on the eggs and larvae of native species (Invasive Species Specialist Group 2018). However, the larger carps (Common Carp (Cyprinus carpio), and other Asian Carps) have much larger impacts because of their larger size and less vulnerability to predators. A related fish, the Prussian or Gibel Carp (C. gibelio), formerly considered a subspecies of C. auratus, is considered to have serious impacts in western Europe and in its newly invaded range in Alberta, Canada (Almqvist 2007; Ruppert et al. 2018).

Goldfish and Common Carp (Cyprinus carpio) have been significant as native hosts of several Asian parasites which have spread to native North American fishes and to fishes of other continents. The parasitic copepod Lernaea cyprinacea has been found on Chinook Salmon (Oncorhychus tshawytscha) in the Willamette River, Oregon (Uzman and Rayner 1958), and in the San Francisco estuary Delta, on four native species - Hardhead (Mylopharodon conocephalus), Sacramento Blackfish (Orthodon microlepidotus), Sacramento splittail (Pogonichthys macrolepidotus), and Sacramento Pike-Minnow (Ptylocheilus grandis), and a non-native White Catfish, Ameiurus catus (Hensley and Nahhas 1975). Lernaea cyprinacea was found on Channel Catfish (Ictalurus punctatus) in the South Carolina coastal zone (Lawler 1978). This ectoparasite is known from a wide variety of fish species around the world. The fish-louse Argulus japonicus is known mostly from Goldfish in North American waters, but it has been collected from Gizzard Shad (Dorosoma cepedianum) and Fathead Minnows (Pimephales promelas) (LaMarre and Cochran 1992). Both of these ectoparasites are known to adversely affect fishes in captivity, but the effect on wild populations is unknown (Shields and Tidd 1974; Hoffman 1977).

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