Exploratorium: Traits of Life: Exhibits

Goldfish "Evolution"

All goldfish can be traced back to a common ancestor, called the crucian carp.

Goldfish breeding started in Japan and China, where the first mutant goldfish was noticed over 2,000 years ago. Since then, people have created many different kinds of fancy goldfish.

All sorts of living things—from dogs and cats to vegetables and flowers—have been selectively bred to suit human needs and tastes. Thousands of years ago, for instance, the Aztecs, Inca, and Maya transformed an unassuming weed called teosinte into the hardy, nutritious, tasty food we call corn.

Genetic changes over time have turned a nondescript little fish into the modern goldfish. You won’t find any of these goldfish in the wild, even though that’s where their ancestors came from. Like all organisms, wild goldfish occasionally produce offspring with mutations—genetic changes that result in odd colors and shapes. People select these mutants and breed them in captivity over many generations, creating new fish with exaggerated traits, like the ones you see above.

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