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Montana Field Guide

Montana Field Guides

Goldfish - Carassius auratus

Non-native Species

Global Rank: G5
State Rank: SNA

Agency Status


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General Description
Goldfish have been introduced and have become established in several locations east of the Continental Divide in Montana. The goldfish is an Asian species that has been bred for bright colors and large, showy fins for the aquarium trade. However, the wild goldfish in Montana are greenish-brown in color and lack the enlarged fins. They hybridize with common carp in some locations outside Montana. Wild goldfish can reach a weight of several pounds. Goldfish can become so numerous in the wild that they crowd out more desirable species. It is illegal to release them in any lake, pond, or stream in the state.

Diagnostic Characteristics
Variable. Ranges from red, orange, black, white or any combination of these in cultured varieties to dark olive brown in individuals that have reverted to the wild.

Observations in Montana Natural Heritage Program Database
Number of Observations: 7

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Prefers Ponds and streams, low turbidities, abundance of vegetation, and little or no current. Known to survive in water 40-80 degrees F.

Food Habits
Mostly phytoplankton but some small aquatic invertebrates eaten.

Coexists with carp at all sites where found in southeast Montana. No goldfish x carp hybrids reported in Montana.

Reproductive Characteristics
Sexually mature in 1-2 yrs. Spawns late spring - mid summer. Incubation: 5-8 days at 65-70 degrees F. Spawns at water temperatures above 60 degrees F.

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Citation for data on this website:
Goldfish — Carassius auratus.  Montana Field Guide.  .  Retrieved on , from