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Beyond the Aquarium: Goldfish Thrive in the Wild

Goldfish, or Carassius auratus, are popular aquarium fish that come in other colors besides gold. In the wild, they are considered to be an invasive species since they can compete for resources and tolerate water pollution better than native fishes. Get to know more about these stocky, popular pets:

Beyond the Aquarium: Goldfish Thrive in the Wild   ©The Earth & I
  • Carassius auratus are known for being gold-colored, but they come in other colors, such as olive green and white. They have a long dorsal fin with 15 to 21 rays and a lateral line with 25 to 31 scales in a lateral series.

  • Goldfish usually live about six or seven years but have lived up to thirty years.

  • Goldfish do not reach the size of carp, but they can reach 23 in (59 cm) in total length and weigh up to 6.6 lbs (3.0 kg). Their usual size is 5.9 to 7.8 in (15 to 20 cm) with weights between 3.5 and 10.5 oz (100 to 300 g).

  • Most adult goldfish thrive well in salinities between 0 to 6 ppt and can survive in water temperatures between 32 to 106°F (0 to 41°C).

  • Researchers speculate that goldfish, introduced in the 1600s, were the first foreign species brought to the United States. The fish have often hybridized with carp.

  • Goldfish have been found in the wild in all fifty states of the United States, but only twice in Alaska—once in Anchorage in 1980 and again in the Nenana River in 2019.

– Source: United States Geological Survey, US Department of the Interior

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