Goldfish
(Carassius auratus)
Learn about the Goldfish, including their identifying features, distribution, habitat, spread, similar species, impacts and our response.
On this page
Identifying features
- between 13 cm and 25 cm, up to 50 cm long
- small mouth, no barbels
- caudal fin (tail) forked
- long dorsal fin (2/3 of the body)
- colour may vary from gold to olive green in wild populations
If you think you have seen a Goldfish, report it.
Where is the species invasive
Goldfish are one of the first aquatic species to be introduced on purpose in North America for the aquarium trade and ornamental water gardens. It ended up in the waterways following the accidental or intentional release of aquarium fish. Goldfish have been reported in water bodies in most Canadian provinces. Due to their popularity in the aquarium trade and among ornamental water gardens owners, it is very likely that there are more Goldfish in our water bodies than what has been reported.
Distribution
The Goldfish is native to central and eastern Asia.
Habitat
In the wild, the Goldfish is often found in ponds, rivers, and lakes where the current is weak, and there is plenty of aquatic vegetation. It tolerates turbid waters (containing suspended matter), with low dissolved oxygen concentrations. It has adapted to harsh climates and cold waters by hiding in the mud and reducing its energy consumption to survive Canadian winters.
Similar species
The Goldfish resembles the Common Carp (Cyprinus carpio). However, Common Carp have a pair of barbels on each side of their mouth and can grow to be 45 cm to 100 cm long. Goldfish can also be mistaken for Koi Fish, an ornamental variety of carp with different colours and patterns (gold, orange, silver, white and black). However, Koi Fish have a pair of barbels at the corner of their mouth, their body is more elongated than the Goldfish or the Common Carp and they range in size from 30 cm to 120 cm.
Koi Fish
Common Carp
Impacts
Ecological impacts
As an omnivorous fish, the Goldfish consumes algae, phytoplankton, zooplankton, fish eggs, insect larvae and detritus. It competes with native fish for available food and space. It is also a potential predator of small fish. The manner with which they feed, similar to that of Common Carp, reduces water clarity. It stirs up silt to dig up rooted vegetation, which can suspend sediment. This prevents plant growth, increases the mortality of eggs and larvae of other aquatic organisms, decreases the efficiency with which other organisms feed and damages the gills of native fish.
Goldfish are recognized as being a vector of diseases which can affect native fish populations. One example is the Cyprinid Herpesvirus 3, a contagious and fatal virus for Common Carp. Goldfish can also stimulate the growth of cyanobacteria passing through its intestinal tract.
Socio-economics impacts
In very large numbers, Goldfish can increase water turbidity and promote the growth of cyanobacteria, which could alter water quality possibly causing the need for restoration.
Response
The Identification Booklet of Freshwater Invasive Species in Quebec from DFO is available to make the detection of the Goldfish easier.
As with many other aquatic invasive species, preventing the deliberate and accidental release of specimens into the environment remains the best way to control their spread. Anyone wishing to dispose of their aquarium and water garden fish must adhere to the relevant safety principles. Don't let it loose and follow the procedures described in the DFO Aquatic Invasive Species Prevention page.
Goldfish populations were eradicated with the use of a pesticide, rotenone. This kind of response needs to be authorized by provincial or federal authorities. Control and management options for aquatic invasive species like Goldfish are in the DFO Control and Management of Aquatic Invasive Species page.
Photo gallery
Related links
- Goldfish identification photos and characteristics
- Science Advice on the Potential of Introducing Live Organisms by the Aquarium, Water Garden, and Live Food Trades in Canada (PDF, 1192 KB)
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