Akagane

One of the oracular koi owned by Tom Swale and Carl Romeo. (If "owned" is the proper word for the relationship...and even if it is, there might be some discussion as to who owns who.)

Akagane is described in WH as "spotted in dark orange-gold and white" and is possibly the "marmalade koi" referred to in WAW. The word akagane (赤金) in Japanese means "copper".

Interestingly, in both TWD and WH Carl uses the Japanese honorific "-sama" when addressing Akagane, suggesting that she's unusually worthy of respect -- possibly because of great age. Late in WAW, Carl corrects Nita's misapprehension that Akagane is a "he". (TWD, WH, WAW)

See also: Doitsu: Koi: Oracular sentients: Pigs and Fishes: Showa.