Abstract

It is a myth that the common carp was originally domesticated in China, maintained through unfounded repetition but with no evidence. The color aberrations called nishikigoi appeared en masse in the 1950s from the Niigata Prefecture in Japan. These ornamental common carp called koi became the most expensive fish, with some prize-winning individuals valued at more than one million dollars. The criteria for domestication or exploited captives are explained, with special attention to fishes. No attempt is made to resolve the taxonomy of the common carp or goldfish, but some nomenclature data are included to assist future systematic revisions. About 2000 years ago, wild common carp were most abundant in the inland delta of the Danube River at the northern edge of the important Roman province Pannonia. The Romans kept fish in specially built piscinae. Common carp were the hardiest fish available, therefore the most capable of surviving the primitive methods of transport of that time. Keeping carp in ponds became more popular in medieval times, when fasting was enforced and fasting food was in demand. The culture of common carp and the building of special ponds gradually became the most profitable branch of agriculture in central Europe. Some unintentional artificial selection had already taken place between the twelfth and the mid-fourteenth century. Deep bodied and variously scaled or scaleless domesticated forms appeared in nearly every pond system. A domestication of a fish that did occur in China was of the much smaller cyprinid called chi, a fish captured there for food since early times. This silver-grey chi, better known as goldfish, Carassius auratus, occasionally appeared as a xanthic form. These red goldfish have been documented since the beginning of the Sung Dynasty in 960 AD. Releasing such rare xanthic forms into Buddhist ponds of mercy was considered a better deed than releasing an ordinary chi. In the 1200s the fish had become tame and were used as ornamental animals in the garden pools of rich landowners. From the late 13th to the mid 15th century, the Chinese began keeping the golden chi in aquarium-like vessels, and soon rich and poor alike became breeders of fancy domesticated goldfish. The variously shaped monstrosities and color aberrants were freaks, but they became very fashionable at that time and still are. More recently other species, such as the guppy, Poecilia reticulata, and the neon tetra, Paracheirodon innesi, became domesticated in the aquarium hobby. Many other fishes kept as ornamentals such as swordtails and platies, discus and angelfishes, as well as those cultured for food such as rainbow trout, channel catfish and sturgeon are merely exploited captives. The occurrence of alternative phenotypes in some species is explained. These altricial (less specialized) or precocial (more specialized) alternatives are caused by differences in the provision of endogenous food (e.g., yolk) in early development, among other factors, and are a response to changing environments. Life history - from indirect, with an externally food gathering larva, to direct without larvae - is constantly adjusted to fit the...