Goldfish

Goldfish weren’t always, well, gold.

Prussian carp, from which goldfish were domesticated, are traditionally a dull, gray-green hue. But mutations and breeding over the years created goldfish' signature orange, red, and yellow pigments found in the over a hundred varieties of the fish today. Goldfish first arrived in Europe in the 1600s and the United States in the 1800s, becoming what is likely the first foreign fish species introduced to North America. (Read more about the history of goldfish here.)

Goldfish have two sets of paired fins and three sets of single fins. They don’t have barbels, sensory organs some fish have that act like taste buds. Nor do they have scales on their heads. They also don’t have teeth and instead crush their food in their throats.

The fish are known for having large eyes and great senses...