Goldfish

Type Description

"Carassius auratus has a long, stocky body. Not all of these creatures have a bright golden color. Wild populations range in color from golden to olive green and even creamy white. The color ranges from olive-bronze to gold along the dorsal surface to silver-white along the ventral part (McDowall, 2000). They can grow to a total length of 41 cm, weigh up to 2 kg and live for 30 years (FishBase, 2004).
Carassius auratus has a long dorsal fin with 15-21 rays. Carassius auratus can be distinguished from other Asian Cyprinids by the presence of a stiff, serrated spine at the origin of the dorsal and anal fins. Asian Cyprinids have a stiff, non-serrated spine (Robison and Buchanan, 1988; Page and Burr, 1991).
Carassius auratus does not reach large sizes like carp. It usually grows to a total length of 120-220 mm, with a maximum total length of 410 mm (Page and Burr, 1991). The average life span is 6-7 years; the maximum age was recorded as 30 years (Robison and Buchanan, 1988)."

Habitat

"The species can live in a wide variety of wetlands. They generally prefer clean waters. They prefer stagnant or slow flowing waters (Billard, 1997). Rivers, streams, ponds and lagoons are the main habitats of this species (Man and Hodgkiss, 1981; Etnier and Starnes, 1993). It is found in eutrophic waters, well vegetated pools and canals (Kottelat and Freyhof, 2007).
Although Carassius auratus grows well at temperatures above 15°C, it will survive in water temperatures between near freezing and 30°C (Street, 2002). However, the species is reported to live better in cold waters.
This species can withstand salinities above 15 ppt for long periods (FishBase, 2004) and can also tolerate low dissolved oxygen conditions (McDowall, 2000). Although Carassius auratus was originally bred in China, it has spread worldwide (Welcomme, 1988). Today it is found in aquariums, ponds and natural habitats all over the world.
In addition to the numerous entries listed in the distribution table, the current status of this fish in the Gulf of Mexico of the Americas can be found on the website of the Gulf States Marine Fisheries Commission (http://nis.gsmfc.org). More information on the non-native distribution of this species within the USA is reported by Nico and Schofield (2010)."

Reproductive Information

Oviparous reproduction is observed. Spawning occurs in shallow water among weeds and several hundred thousand small eggs (1-2 mm diameter) are laid simultaneously (McDowall, 2000). Female fish can produce 3-10 lots of eggs at 8-10 day intervals. Cold water in winter is necessary for proper reproductive development (FishBase, 2004); ovarian development occurs at low water temperatures in winter (Yamamoto and Tagawa, 2000). Spawning usually occurs in waters where tree roots are exposed to water (Schwartz, 1964). Eggs are sticky, attached to aquatic plants or submerged objects (Kottelat and Freyhof, 2007).

Lifecycle

Eggs hatch in about a week. Young individuals are attached to aquatic plants for several days while the yellow yolk sac is absorbed (McDowall, 2000). Juveniles require higher temperatures to grow.

Nutrition Information

This species feeds mainly on plankton, benthic invertebrates, plant material and detritus (Kottelat and Freyhof, 2007). A variety of aquatic plants (including algae), detritus, crustaceans, worms, small insects and snails are included (FishBase, 2004; McDowall, 2000).

General Impact Information

"Some countries have reported some negative ecological impacts after the introduction of this species. They prey on the eggs, larvae and adults of native fish (Morgan and Beatty, 2004), increase water turbidity and consume aquatic vegetation (Richardson et al., 1995).
Impact on Habitats: The presence of these fish can increase the risk of ""primary production"" in water. Some studies have shown that the growth of cyanobacteria increases as they pass through the intestines of aquarium fish.
Impact on Biodiversity: Cyanobacteria, diatoms, nematodes, insect larvae, green algae and some terrestrial insects have been detected in goldfish stomach contents collected from the Vasse River in Western Australia (Morgan and Beatty, 2004).
This species is blacklisted in the IUCN Global Invasive Species Database."

General Management Information

"Due to its widespread international distribution, the species is very difficult to control.
Physical Control: Gill nets, drift nets and electrofishing can be used to control goldfish populations (Morgan and Beatty, 2004)."

General Pathway Information

It is commercially introduced to Turkey for ornamental and aquarium fisheries. Distribution routes: Same as in other countries. These are ornamental and pet trade.

Notes

References