A freshwater cyprinid (family Cyprinidae) native to East Asia, one of the earliest fish domesticated purely for ornamental purposes. Domestication began in China over 1,000 years ago (Song Dynasty) from wild Prussian carp or closely related forms. Wild-type fish are olive-brown; centuries of selective breeding have produced the characteristic gold/orange color, plus hundreds of varieties (fantail, telescope eye, bubble eye, lionhead, ranchu, oranda, ryukin, etc.) with extraordinary variation in body shape, fin length, eye form, and coloration. Adults weigh from a few grams to >1 kg depending on variety and environment. They are omnivorous, eating algae, plants, insects, and detritus. Hardy and tolerant of poor water conditions. They are used in scientific research for vision, learning, behavior, neuroendocrinology, and regeneration. They can survive brief periods of anoxia by producing ethanol (anaerobic glycolysis). Feral goldfish are invasive in many freshwater systems. The genome is sequenced (2n=100, allotetraploid—duplicated genome). Lifespan: 10–15 years commonly, up to 40+ years. IUCN: Least Concern.