KYOTO--A surreal scene awaits visitors to dyeing studio Arashiyama Yusai-tei in the city’s Ukyo Ward at this time of year.

In Japanese goldfish auction jargon, bidders use the following codes for numbers one through 10: Sen, Ri, Kawa, Tsuki, Cho, Ten, Ka, Tsu, Gan, Maru. Now is the season when goldfish wholesale ...