Goldfish

Goldfish, photo courtesy of Windsor Aguirre, Gulf Coast Research Laboratory Museum Institute of Marine Sciences and Gulf States Marine Fisheries Commission, http://nis.gsmfc.org/.

Characteristics

Goldfish have many unusual body forms and occur in a variety of colors. Bulge-eyed and multiple tailed forms are commonly produced for aquarium display, but normal body form is robust and laterally compressed. The natural color is olive-brown dorsally to bronze-gold laterally and yellowish-white ventrally. Black, gold, bronze, orange, red, pink, and white, or combinations of these colors are often found. Goldfish resemble Common Carp but lack barbels on upper jaw.

Distribution

Goldfish Distribution

Goldfish is an exotic species that is widely distributed in Iowa waters. The origin of most of these specimen is from aquarium or bait buckets. Wild populations of goldfish have been reported in the Mississippi, Missouri, Des Moines, Iowa, Cedar and Wapsipinicon rivers. Several man-made recreational lakes, river impoundments, and surface mine lakes also have reproducing Goldfish populations. They do not appear to jeopardize the integrity of native fishes and seldom spread far.

Foods

This fish feeds on zooplankton and aquatic larval insects.

State Record

State Records are not documented for non-game species.

Expert Tip

Iowa law prohibits release of Goldfish into public water, however Goldfish can be used as bait (placed on a hook while fishing).

Details

The Goldfish is a species exotic to Iowa, mostly introduced from bait buckets or aquarium. Wild populations have been found throughout the forested portions of northeast Iowa including several in the Cedar, Shellrock, Winnebago and Mississippi rivers and their tributaries. The Goldfish has also been collected in sporadic locations in the remainder of Iowa with specimens found in the Iowa, Des Moines, Skunk and Missouri Rivers. Reproducing Goldfish populations are also found in many man-made lakes and impoundments throughout the state.  

Self-sustaining populations of Goldfish can be found in natural standing water habitats along streams and below hatcheries where large populations are maintained by escape. They can also be found in large impoundments where they are often used as bait. The Goldfish, being very tolerate of turbidity and high organic content, can at times be found in the most polluted streams. In Iowa, goldfish select fairly specific habitats, sluggish water or pools with abundant vegetation, thus limiting their distribution. In addition, cultured Goldfish are easy prey for predators because of their showy colors and domesticated nature. 

Goldfish have many unusual body forms and occur in a variety of colors. Bulge-eyed and multiple tailed forms are commonly produced for aquarium display, but normal body form is robust and laterally compressed. The natural color is olive-brown dorsally to bronze-gold laterally and yellowish-white ventrally. Black, gold, bronze, orange, red, pink, and white, or combinations of these colors are often found. Serrated spinous rays occur at the front of the dorsal and anal fins, which distinguishes goldfish from the native minnows.

Superficially, Goldfish resemble Common Carp, but several features separate them. Goldfish lack barbels on the upper jaw, and the thin-lipped mouth is terminal. Body scales on Goldfish do not have the dark spot, and no cross hatching pattern is present. Internally, the pharyngeal teeth of Goldfish are arranged along a single row in 4-4 sequence, and they have heavy arches with the crowns at an angle.

The complete lateral line contains from 25 to 30 scales. The dorsal fin, which is much longer than those of native minnows, has from 15 to 19 soft rays, while the pectoral fins have from 15 to 17 soft rays, and the pelvic fins usually have 9 soft rays. Hybridization with Common Carp is known where both species inhabit the same waters. Spawning takes place from April through August as the female scatters adhesive eggs in shallow, vegetated water at random. Large female Goldfish produce over 200,000 eggs.

This fish feeds on zooplankton and aquatic larval insects. In Iowa, adult fish typically range from 8 to 16 inches in length and weigh up to 2 pounds. This species is used extensively as bioassay animals for scientific purposes and has widespread use because it is hardy and easily kept in confinement. Iowa law prohibits release of Goldfish into public water, however Goldfish can be used as bait (placed on a hook while fishing).

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames.

Photo Credit: photo courtesy of Windsor Aguirre, Gulf Coast Research Laboratory Museum Institute of Marine Sciences and Gulf States Marine Fisheries Commission.


Return
Present in these Iowa water bodies:
Lake/Stream County Location Acres/Length
Coralville Reservoir Johnson 4 miles north of Iowa City 5280.00
Iowa River (Marshalltown to Coralville Lake) Iowa This stretch is located in Marshall, Tama, the SW corner of Benton, Iowa, and Johnson County. A popular access is at the Hwy 21 Access, which is part of the Iowa River Corridor Wildlife Area, just south of Belle Plaine. 104.00