Goldfish, Carassius auratus
Goldfish, Carassius auratus, Juvenile. Fish caught from a pond in Frye Mesa, Arizona, July 2005. Length: 5.5 cm (2.2 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Goldfish, Carassius auratus, Juvenile. Fish caught from a hot spring in Eastern Idaho, June 2018. Length: 7.2 cm (2.8 inches). Length: 5.1 cm (2.0 inches). Catch, photograph, and identification courtesy of Ben Cantrell, San Diego, California.
Goldfish, Carassius auratus. Fish caught from the Topsy Reservoir, Keno, Oregon, July 2005. Length: 10.5 cm (4.1 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Goldfish, Carassius auratus. Fish caught from a hot spring in Eastern Idaho, June 2018. Length: 11.5 cm (4.5 inches). Catch, photograph, and identification courtesy of Ben Cantrell, San Diego, California.
Goldfish, Carassius auratus. Fish caught in a residential pond in greater Milwaukee, Wisconsin area, June 2016. Length: 14 cm (5.5 inches). Catch, photograph, and identification courtesy of Ben Cantrell, San Diego, California.
Goldfish, Carassius auratus. Fish caught in a residential pond in greater St. Paul, Minnesota area, June 2021. Length: 14 cm (5.5 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.
Goldfish, Carassius auratus. Fish caught in a residential pond in greater Milwaukee, Wisconsin area, June 2016. Length: 14 cm (5.5 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
The Goldfish, Carassius auratus, is a member of the Carp and Minnow or Cyprinidae Family, and is known in Mexico as carpa dorado. Globally, there are five species in the Carassius Genus, of which one, this species is found in Mexico’s freshwater systems. The Goldfish is native to East Asia and was first selectively bred in ancient China over 1,000 years ago. There are currently over 300 different breeds. They were first introduced to North American in 1850 and are know found globally.
The Goldfish have a thick-set, elongated stout body with a thick and short caudal peduncle. Todays breed vary greatly in size, body shape, fin configuration and color variations of black, brown, orange, red, white and yellow. In the wild they are normally gold to olive green to creamy white in color. Males and females have similar colorations however they are sexually dimorphic with males having concave anal fins and females convex anal fins. The juveniles maintain a metallic brown color for their first year and then transition into their adult colors. Their head is broadly triangular with a broad space between the very large eyes, and long snout, and a mouth that ends just before the eyes. They have pharyngeal teeth in their throats that are utilized to crush food. They have a keen sense of hearing and smell. Their anal fin has 2 or 3 spines, the first of which is serrated, and 4 to 7 rays; their caudal fin has 17 to 19 rays and is deeply forked; their dorsal fin has 3 or 4 spines, the first of which is serrated, and 14 to 20 rays and a long base; their pectoral fins have 15 to 17 rays; and their pelvic fins are broad and short. They have 37 to 47 gill rakers. They are covered with small scales except on the head. Their lateral line is complete.
The Goldfish is a gregarious schooling species that are found in ditches, lakes, ponds, reservoirs and rivers that have either no water flow or very limited water flow at depths up to 20 m (66 feet). They are found primarily in fresh water systems but also in brackish water with a salinity up to 17 ppt, well vegetated ponds and canals. They reach a maximum of 48 cm (19 inches) in length and 3.0 kg (6 lbs 10 oz) in weight. They are an omnivore that feed on a wide range of food including small crustaceans, detritus, insects and plants. They are known to practice cannibalism. In turn they are preyed upon by various gulls and herons, large fishes, and turtle. Goldfish can tolerate water temperatures between 0oC (32oF) and 30oC (86oF) but require temperatures in excess of 15oC (59oF) to grow and reproduce.
The Goldfish have the ability to survive for short periods of time in oxygen depleted waters and in frozen water bodies. Reproduction is oviparous in annual breeding cycles and occurs when water temperatures reach 15oC (59oF) to 20oC (68oF). Each female spawns with several males and deposits eggs every 8 to 10 days 3 to 10 times per year. The eggs attach to aquatic vegetation, that are externally fertilized simultaneously and hatch within 48 to 72 hours. Their larvae are pelagic. They require cold water episodes during the winter months for proper ova development. They are known to readily hybridize with carp.
The Goldfish was introduced to Mexico and is a resident of the freshwater systems. They are common but their specific ranges have not been well documented.
The Goldfish is a straightforward identification it being the only Asian Cyprinid to have serrated first anal and first dorsal spine.
From a conservation perspective the Goldfish is currently considered to be of Least Concern with stable, widely distributed populations. Under proper conditions they have rapid growth rates and explosive populations. They are the mostly widely utilized aquarium fish globe being easy to maintain, is easy to propagate and have long lifespans. They are also utilized for ornamental purposes stocking outdoor ponds. They have become widely distributed in the wild and highly invasive due to aquarium releases and intentional introductions. Their introductions have had major adverse ecological impacts on native environments causing habitat alternations, modifications of the natural benthic communities and they strongly compete and subsequently eradicate native species. In some regions where they have been introduced that are considered pests and have been difficult to eradicate. They are raised extensively via aquaculture and utilized as a live food fish for larger fish maintained in captivity, for biological control and as laboratory animals. They are sold commercially to recreational fishermen for use as a live bait. They are eatable by humans but not widely consumed. They are scientifically interesting due to their senses of vision being able to differentiate between blue, green, red and ultraviolet, keen sense of hearing, learning abilities as they are able to recognize individual humans, memory spans of up to three months, and their ability to distinguish between different shapes, colors, and sounds.