In modern Shimo-Ina County, Nagano Prefecture, the carp cultivation industry markedly expanded, diverging from the common paddy-based approach to primarily utilize ponds. This paper scrutinizes the evolution of carp farming from a supplementary activity to rice cultivation into an independent, profitable industry. Integral to this growth were the Tenryu River flood control initiatives, which unintentionally prepared the groundwork for pond aquaculture. Additionally, the Ministry of Agriculture and Commerce's investigations promoted the simultaneous practice of rice farming and carp cultivation, acknowledging the substantial income benefits. Shimo-Ina County's inland position coupled with its market accessibility substantially contributed to the industry's prosperity and regional economic vitality.
Takako Kimura (Sat,) studied this question.