Common carp are the most widely farmed food fish in the world. The Germans (Doitsu) selectively bred carp to have few or no scales to aid in the processing. During the Meija Erra (1868-1912) the Japanese bred some of their colored koi to two varieties of German carp. One is the leather carp without any scales and the other is a mirror carp that has large mirror scales along each side of the dorsal fin and also along the lateral line on each side of the koi. These are call Doitsu (German) koi. You can find Doitsu koi in most of the varieties of Japanese Nishikigoi (brocaded carp).