Carassius auratus (Linnaeus, 1758)

Common Name: Goldfish

Synonyms and Other Names:

Copyright Info

Identification: Carassius auratus has an elongated, stocky body. Not all individuals have the well-known bright gold color. Wild populations vary in color from gold to olive green or even creamy white. It possesses a long dorsal fin with 15 to 21 rays and a hard serrate spine at the origin of the dorsal and anal fins. The lateral line is complete, with 25–31 scales in a lateral series. It can be distinguished from other Asian cyprinids by the presence of a stiff, serrate spine at the origin of the dorsal and anal fins. Asian cyprinids have a stiff, non-serrate spine at this position (Robison and Buchanan, 1988; Page and Burr, 1991). The anal fin of the male is concave, whereas on the female it is convex. It does not reach the large size attained by carp. The usual life span is 6 to 7 years, with a maximum of 30 years recorded (Robison and Buchanan, 1988). Distinguishing characteristics were provided in Wheeler (1978), Raicu et al. (1981), Trautman (1981) and Page and Burr (1991). Identification keys that include this species and photographs or illustrations are provided in most state and regional fish books (e.g., Hubbs and Lagler 1958; Becker 1983; Etnier and Starnes 1993). There has been considerable confusion concerning the taxonomic status of this species. Many authors have recognized two subspecies in its native range: C. a. auratus (the goldfish, Chinese goldfish, or Asian goldfish) from Asia, and C. a. gibelio (the Prussian carp, gibele carp, or European goldfish) from eastern Europe (Raicu et al. 1981). Others have concluded that the goldfish is a subspecies of the crucian carp Carassius carassius (i.e., C. c. auratus). More recently, it has been reported that C. auratus is a tetraploid derivative of C. carassius (references in Jenkins and Burkhead 1994). There are many mutant goldfish varieties and these exhibit a broad range of body forms and colors. Howells (1992b) reported that some exotic fish experts believe that "goldfish" typically observed in U.S. waters is actually a crucian carp x goldfish hybrid. In addition, goldfish commonly hybridizes with common carp Cyprinus carpio, giving rise to individuals that are intermediate in morphology between the two parent species. Goldfish has been widely and repeatedly stocked in the United States from many points of origin, including both Asia and Europe. As such, U.S. populations represent a complex of morphologically and taxonomically diverse forms.

Size: Typically grows to 120 to 220 mm SL, with a maximum of 410 mm SL (Page and Burr, 1991).

Native Range: Eastern Asia, including China and perhaps adjacent regions (Japan, Republic of Korea); also possibly parts of Europe if C. auratus gibelio is a valid subspecies and not just a feral introduction (Raicu et al. 1981).

Great Lakes Nonindigenous Occurrences: This species has been recorded from virtually every state. 

Carassius auratus has also been collected in Puerto Rico (Erdman 1984; Lee et al. 1983).

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Carassius auratus are found here.

Full list of USGS occurrences

State/ProvinceFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
IL191720183Lake Michigan; Little Calumet-Galien; Pike-Root
IN199920041Little Calumet-Galien
MI1880202119Au Gres-Rifle; Black-Macatawa; Clinton; Detroit; Great Lakes Region; Huron; Kalamazoo; Lake Erie; Lake Huron; Lake Michigan; Lake St. Clair; Lower Grand; Muskegon; Ottawa-Stony; Raisin; Saginaw; St. Clair; Tittabawassee; Upper Grand
MN197520042Lake Superior; St. Louis
NY1982201916Ausable River; Buffalo-Eighteenmile; Cattaraugus; Chaumont-Perch; Eastern Lake Erie; Great Lakes Region; Irondequoit-Ninemile; Lake Erie; Lake Ontario; Lower Genesee; Niagara River; Oak Orchard-Twelvemile; Oneida; Raisin River-St. Lawrence River; Salmon-Sandy; Seneca
OH1927201712Ashtabula-Chagrin; Black-Rocky; Cedar-Portage; Chautauqua-Conneaut; Cuyahoga; Huron-Vermilion; Lake Erie; Lower Maumee; Ottawa-Stony; Sandusky; St. Marys; Upper Maumee
PA197820142Chautauqua-Conneaut; Lake Erie
VT199219921Mettawee River
WI196920137Duck-Pensaukee; Lake Michigan; Lower Fox; Manitowoc-Sheboygan; Milwaukee; Pike-Root; Wolf

Table last updated 12/2/2023

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

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

Means of Introduction: DeKay (1842) reported that goldfish first was brought into the U.S. shortly after the early part of the seventeenth century. Citing that work, Courtenay and Stauffer (1990) reported that the first recorded goldfish releases in the United States occurred during the late 1600s, and they suggested that these earliest introductions resulted from intentional releases by settlers wanting to add it to the North American fish fauna, as opposed to goldfish escaping from ponds. DeKay (1842) reported, likely in reference to the early 1800s, that goldfish in the United States was considered an ornamental species rather than a food fish, even though the fish freely reproduced in ponds in New York and adjacent states. During the late 1800s the U.S. Fish Commission raised the species and was responsible for distributing it to many states, mainly to meet the demand for fish for aquaria, fountains, and ornamental lakes (McDonald 1886, 1893). Johnson and Becker (1980) stated that goldfish was introduced to Wisconsin through a fish exchange program with the Nebraska Fish Commission in the early 1900s. Brock (1960) stated that this species was established in Hawaii before 1900 and that there had doubtless been many reintroductions. Jordan and Evermann (1905) indicated that these fish were introduced into Hawaii from China, but stated that there is no record as to the date. They did state that shipments of goldfish were being made to San Francisco (California) as early as 1867. More recent introductions of C. auratus in the United States were the result of escapes from hatcheries and ponds, escapes and releases of baitfish, and aquarium releases (Knapp 1953; Courtenay and Hensley 1979; Courtenay et al. 1984; Pflieger 1997). In Michigan, the report of the State Superintendent of Fisheries for 1877-1878 states that C. auratus was first introduced into the ponds of the State Hatchery in 1878 (Eschmeyer 1938).

Status: Established or reported in all states except Alaska. Even though the species is one of the most widely distributed foreign fishes in North America, much of its established range is restricted to only portions of certain drainages (Courtenay and Stauffer 1990). Some areas may represent repeated escapes or releases rather than established populations (Lee et al. 1980 et seq.). Courtenay et al. (1984) reviewed the literature and concluded that the species had been taken in the wild in all states except Alaska. They denoted the species as being established in 16 of the lower 48 states, including California, Delaware, Georgia, Idaho, Illinois, Indiana, Iowa, Kentucky, Maryland, Massachusetts, Michigan, Nebraska, Nevada, New Hampshire, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, Washington, and Wisconsin. Courtenay et al. (1984) listed it as possibly established, status uncertain, in 17 additional states: Alabama, Arizona, Arkansas, Colorado, Connecticut, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Montana, New Jersey, New Mexico, North Carolina, North Dakota, Oregon, and Wyoming. In recent years, the existence of breeding populations has been confirmed for some of the above names states, for example, Connecticut (Whitworth 1996), Missouri (Pflieger 1997), and Wyoming (Stone 1995). Bond (1994) noted that it is present locally in warm, still waters of Oregon. The species is also known from all the major islands of Hawaii and Brock (1960) stated that it was established in that state before 1900. Devick (1991) listed it as definitely established in Hawaii. This species has been recorded from Florida, Maine, Utah, Vermont, and West Virginia, but there is as yet no available data indicating the presence of self-sustaining populations. Countryman (1975) listed it as "naturalized" in Vermont, which suggests presence of reproducing populations. In a recent paper, Courtenay (1993) listed goldfish as established in most states except Alaska and Florida.

Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...


Current research on the environmental impact of Carassius auratus in the Great Lakes is inadequate to support proper assessment.

Little is known about the ecology of the goldfish in North America. In most states, it is not considered a "pest species." Nevertheless, this species has the potential to produce large populations in American waters (references in Courtenay and Hensley 1979, Moyle 1976, Trautman 1981).

According to Moyle (1976), goldfish probably compete with native fishes for food and space; and similar to common carp, large populations of this species can greatly disturb sport fish habitats. The Sacramento sucker (Catostomus occidentalis) is one native species that suffers in the presence of goldfish (Moyle 1976). However, Laird and Page (1996) concluded that goldfish in Illinois appear unable to compete with native fishes and reported that the species becomes established only in severely disturbed areas. Based on a series of artificial pond experiments, and observations of a feral population, Richardson et al. (1995) found that goldfish is a benthic herbivore whose behavior often results in visible increases in turbidity and decreases in aquatic vegetation.

In Nevada, the establishment C. auratus in Manse Spring was believed to be a major reason for the initial decline during the early 1960s of populations of a subspecies of the now endangered Pahrump poolfish (Empetrichthys latos latos) (Deacon et al. 1964, Lee et al. 1980 et seq.), possibly competing with adult E. l. latos and preying on their young.

There is little or no evidence to support that Carassius auratus has significant socio-economic impacts in the Great Lakes.

Current research on the beneficial effect of Carassius auratus in the Great Lakes is inadequate to support proper assessment.

Carassius auratus has been cultured as both a popular bait fish and aquarium species in the United States, although the extent of its importance in the Great Lakes is unknown (Litvak and Mandrak 1993, see remarks).

Management: Regulations (pertaining to the Great Lakes)
Canadian federal law dictates that no person shall use as bait, or possess for use as bait, in any province any live or dead goldfish (Maritime Provinces Fishery Regulations § SOR 93/55). Provincial law in Quebec also states that goldfish are not to be used as bait (Quebec Fishery Regulations § SOR 90/214).

In the state of New York, it is illegal to use or sell goldfish larvae for bait, and goldfish larvae taken in nets operated pursuant to baitfishing are to be destroyed immediately (NY ECL § 11-1315). In Minnesota, goldfish are a regulated invasive species, making introduction of the species without a permit illegal (Minn. Admin. Rules § 6216.2060, Minn. Admin. Rules § 6216.0265). In the state of Pennsylvania, it is unlawful to use or possess goldfish as baitfish while fishing (58 PA Code § 63.44). In the state of Wisconsin, goldfish are a restricted invasive species (Wis. Admin. Code § NR 40.05).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

There are no known biological control methods for this species.

Goldfish can be managed by physical removal, particularly in small ponds and shallow or enclosed embayments (Morgan et al 2005). 

Yamamoto et al. (2006) noted that physical drawdown of water levels has significant negative effects on cyprinid spawning abilities in Lake Biwa, Japan. Carassius spp. and Cyprinus carpio eggs were notably reduced after collection when water levels were lowered by 30 cm, and as little as a 10 cm reduction can significantly reduce available shallow, litter-accumulated spawning areas preferred by cyprinids (Yamamoto et al. 2006).

Of  the four chemical piscicides registered for use in the United States, antimycin A   and rotenone  are considered “general” piscicides (GLMRIS 2012).  However, goldfish are noed to have a relatively high tolerance to these piscicides (Gilderhus et al 1981, Marking and Bills 1976, Marking and Bills 1975, Marking 1975, Schoettger and Svendsen 1970, Walker et al 1964, Turner 1956) - thus levels sufficient for goldfish control would be likely to disproportionately harm desirable native species. 

Liming is listed by CLearwater et al (2008) as a potential control method for goldfish.

Increasing CO2 concentrations, either by bubbling pressurized gas directly into water or by the addition of sodium bicarbonate (NaHCO3) has been used to sedate fishes with minimal residual toxicity, and is a potential method of harvesting fish for removal, though maintaining adequate CO2 concentrations may be difficult in large/natural water bodies (Clearwater et al. 2008 ). CO2 is approved only for use as an anesthetic for cold, cool, and warm water fishes the US, not for use as euthanasia, and exposure to NaHCO3 concentration of 142-642 mg/L for 5 min. is sufficient to anaesthetize most fish (Clearwater et al. 2008). However, goldfish are tolerant to hypoxic conditions (Roesner et al 2008) so this method may have limited effect or cause disproportionate mortality of non-target fish.

It should be noted that chemical treatment will often lead to non-target kills, and so all options for management of a species should be adequately studied  before a decision is made to use piscicides or other chemicals. Potential effects on non-target plants and organisms, including macroinvertebrates and other fish, should always be deliberately evaluated and analyzed. The effects of combinations of management chemicals and other toxicants, whether intentional or unintentional, should be understood prior to chemical treatment. Boogaard et al. (2003) found that the lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2’,5-dichloro-4’-nitrosalicylanilide (niclosamide) demonstrate additive toxicity when combined. In another study on cumulative toxicity, combinations of niclosamide and TFM with contaminants common in the Great Lakes (pesticides, heavy metals, industrial organics, phosphorus, and sediments) were found to be mostly additive in toxicity to rainbow trout, and one combination of TFM, Delnav, and malathion was synergistic, with toxicity magnified 7.9 times (Marking and Bills 1985). This highlights the need for managers to conduct on-site toxicity testing and to give serious consideration to determining the total toxic burden to which organisms may be exposed when using chemical treatments (Marking and Bills 1985). Other non-selective alterations of water quality, such as reducing dissolved oxygen levels  or altering pH, could also have a deleterious impact on native fish, invertebrates, and other fauna or flora, and their potential harmful effects should therefore be evaluated thoroughly.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.


Remarks: The goldfish is thought to be the first foreign fish species introduced to North America (DeKay 1842; Courtenay et al. 1984). In the United States, large numbers are cultured as bait and as forage for sport fishes, as well as for the production of young fish that are then sold in the aquarium trade, mostly as live food (i.e., feeder fish) for carnivorous ornamental fishes. Although brightly-colored forms popular in the aquarium trade are occasionally taken in North American waters, the surviving progeny of these colorful individuals typically are the natural, cryptic olive-green coloration, partly as a result of selective predation by other animals. In nature, goldfish often hybridize with common carp Cyprinus carpio producing reproductively fertile offspring; cross fertilization and back-crossing is common in some areas, for instance polluted habitats, and in such places hybrid offspring may outnumber the parent species (Trautman 1981; Page and Burr 1991). Goldfish grows rapidly and thus is limited in their usefulness as a forage fish. The use of goldfish as baitfish is prohibited in some states. Detailed background information on the occurrence of this species in the United States was provided by Becker (1983). Knapp (1953) stated that this species is used as a hardy bait fish in many areas or crossed with carp for same purpose. He reported that a population of these hybrids was found in Buffalo Lake, Randall County, in the Texas panhandle. In their summary table, Bailey and Smith (1981) indicated that Carassius auratus is widely distributed in the Great Lakes basin.

Voucher specimens: Alabama (TU 16398, 51965, 52008, 52022, many others), Arkansas (TU 7071, 44838, 46903), California (USNM 4485, 38016), Georgia (UGAMNH, USNM 110111), Hawaii (BPBM 1803, 3623, specimens discarded in1969), Illinois (INHS 710, 726, many others including hybrids with carp), Maryland (USNM 85073, 85217, 85795, 238723, 271219, 271221), Massachusetts (USNM 020091, 77787), Michigan (TNHC 671), Nevada (TU 94343), New York (USNM 020271, TU 36678), Ohio (USNM 28416, TU 6566), Pennsylvania (USNM 335461), Rhode Island (USNM 21658), South Carolina (USNM 271220), Texas (TCWC 0455.01, 1045.01, 1030.01, TNHC 6969, many others), Virginia (USNM 37789, 85694, 283639), West Virginia (USNM 64464).

References (click for full reference list)

Author: Nico, L.G., P.J. Schofield, J. Larson, T.H. Makled, A. Fusaro, and C. Morningstar

Contributing Agencies:

Revision Date: 10/29/2021

Peer Review Date: 8/2/2013

Citation for this information:
Nico, L.G., P.J. Schofield, J. Larson, T.H. Makled, A. Fusaro, and C. Morningstar, 2023, Carassius auratus (Linnaeus, 1758): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 10/29/2021, Peer Review Date: 8/2/2013, Access Date: 12/2/2023

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.