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

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).

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

Environmental	Socioeconomic

Realized:
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.

Potential:
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).

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.

Control
Biological
There are no known biological control methods for this species.

Physical
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).

Chemical
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.

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).