Doitsu-goi (ドイツ鯉) originated by crossbreeding quite a few diverse proven varieties with "scaleless" German carp (generally, fish with only only one line of scales along each side in the dorsal fin). Also published as 独逸鯉, 4 main kinds of Doitsu scale designs exist. The commonest type (referred to previously mentioned) https://www.propanraya.com/cara-merawat-ikan-koi-agar-tetap-sehat-dan-indah-di-kolam-rumah