Map of the sampling sites of Carassius auratus. Map showing water systems, islands, and fish markets where Carassius auratus specimens were collected. Specimens from waters numbered 1-16, 28, and 31 were collected previously by Yamamoto et al. [6]. Locality numbers correspond to those in Additional file 1 and Figure 6: 1, Lake Sakasazawa; 2, Lake Fukushimagata; 3, Lake Inawashiro; 4, Urano River; 5, Lake Kasumigaura; 6, Magame River; 7, Kamidokan Moat; 8, Nagara River; 9, Lake Biwa; 10, Kako River; 11, Takatsu River; 12, Shimanto River; 13, Shigenobu River; 14, Iki Island; 15, Tatara River; 16, Chikugo River; 17, Tanegashima Island; 18, Amami-oshima Island; 19, Tokunoshima Island; 20, Iheya Island; 21, Izena Island; 22, Okinawa Island; 23, Tokashiki Island; 24, Zamami Island; 25, Kume Island; 26, Minamidaito Island; 27, Ishigaki Island; 28 Amur River; 29, Taipei fish market; 30, Donguan fish market; 31, Yangtze River; 32, Kai Ping; 33, Fangzheng hatchery; 34, Qi hatchery; 35, Jiujiang hatchery; and 36, Wuhan hatchery. The inset shows a map of Eurasia denoting the present sampling area.