Goldfish (Carassius auratus)

person holding a large orange goldfish Photo courtesy City of Burnsville

Description

Appearance

Physical characteristics vary greatly. Coloration can include olive green, gold, white, red or orange. The common goldfish lack barbels on the upper jaw, have no scales on their head and their eyes are relatively large. Goldfish (Carassius auratus) are closely related to koi (Cyprinus rubrofuscus) and common carp (Cyprinus carpio), which could be misidentified as goldfish. The typical length of a goldfish is between 5-8 inches, but they can reach close to 2 feet long. They can weigh up to 6 pounds (USGS). Goldfish are often found in groups of a dozen or more, up to several thousand fish.

Body shape and fins

Generally, goldfish have an elongated, stocky, football-shaped body. They have a long dorsal fin (with 15-21 fin rays), and a forked tail fin.

Photos courtesy Jess Norby, Carver County Water Management Organization.

Biology

Goldfish are a freshwater fish in the carp family. They are omnivorous bottom-feeding foragers and crush food such as insects with their pharyngeal teeth. Goldfish are highly tolerant of turbid waters, temperature fluctuations and low levels of dissolved oxygen. Typical habitat includes streams and pools with submerged vegetation. Goldfish reproduction often coincides with fluctuations in the environment. Lifespan is typically 6-7 years.

Origin and spread

The native range of goldfish includes Eastern Asia and parts of Europe. Their high tolerance for a variety of conditions make them popular pets. Recently, there have been many reports of wild populations of goldfish in Minnesota waters (see EDDMapS for reports). These populations are likely the result of people illegally releasing pet goldfish into Minnesota waters.

Don’t be fooled by these look-alikes

Prussian carp, Carassius gibelio (invasive, has not been detected in Minnesota)
Crucian carp, Carassius carassius (invasive, has not been detected in Minnesota)
Common carp, Cyprinus carpio (invasive)
Koi, Cyprinus rubrofuscus (invasive)
Grass carp, Ctenopharyngodon idella (invasive)

Regulatory classification

Goldfish (Carassius auratus) and koi are regulated invasive species in Minnesota, which means it is legal to possess, sell, buy, and transport, but it is illegal to release them into the environment. You may not use goldfish as fishing bait in Minnesota.

Control methods

Like common carp, goldfish populations are very difficult to eradicate. There are several potential options available to manage goldfish including:

basin manipulation (e.g., dewatering or drawdown)
physical removal (e.g, netting, seining, capturing)
predator stocking (e.g. northern pike or largemouth bass)
pesticide use (e.g. rotenone)

These options will require a permit from the DNR in most instances. Optimal removal methods vary depending on the type of basin (storm water retention basin, public water, or private pond). With any method, control is not a guarantee; therefore continuous monitoring may be needed to assess goldfish presence or absence.

Adaptive management might also be needed depending on the system. It is recommended to base management on the goldfish behavior, spawning locations and movement. These indicators may help to determine the correct gear and management option for your project.

This handout contains best management practices for goldfish control and information on permitting. Please reach out to your local AIS Specialist with additional questions.

Threat to Minnesota waters

Goldfish populations may cause recreational, economic and ecological damage. Infestations change how residents and visitors use and enjoy Minnesota waters.

Goldfish reproduce rapidly and can quickly number in the hundreds or thousands.
Large populations can outcompete native fishes and in some instances disrupt sport fisheries.
Goldfish can increase turbidity by stirring up the sediments when feeding, resulting in a decline in aquatic vegetation and water quality.
The resulting changes in vegetation can impact habitat for native fish.
Goldfish can be a host for disease (e.g., Koi herpesvirus [KHV] and carp edema virus [CEV]) that can contribute to large die-offs, resulting in an unhealthy fish community

What you should do

Report new populations

Report new occurrences of goldfish to the DNR immediately by logging in and submitting a report through EDDMapS. The report will be verified by your DNR Invasive Species Specialist.

two people standing in a stream to net goldfish

Photos courtesy Jess Norby, Carver County Water Management Organization.

Help prevent the spread

People spread goldfish primarily through the illegal release of fish kept in ponds or as pets. It is inhumane and illegal to release goldfish into the environment. Like any other domesticated animal, your fish deserve proper care. See below for alternatives to release. Goldfish can also escape into natural waterways from human-made ponds. To avoid this, build ponds away from other waters and areas prone to flooding.

Alternatives to release can be found on the Responsible Buyers Webpage and include:

Contacting a retailer for possible returns.
Rehoming your pet by giving it away, donating it to a local school, or trading with other responsible hobbyists.
Bringing your pet to a humane society or Habitattitude™ animal surrender event.
If the fish is sick, the best option is to contact a veterinarian or pet retailer for guidance on treatment or euthanasia of the pet.

Pledge to protect Minnesota waters

Pledge to protect Minnesota waters from aquatic invasive species. These AIS are plants, animals and diseases that do not naturally occur in our waters and may cause harm to the environment, the economy, human health or natural resources. Your pledge demonstrates your commitment and care to prevent the spread of AIS in Minnesota. Take the pledge.

Invasive aquatic animals

Aquatic Invasive Species