How Ojiya Production Works
Ponds, parent fish, selection and the autumn harvest — the production system behind the birthplace city's fish.
| Producers | Niigata Prefecture counts 300+ producers, the most of any prefecture |
|---|---|
| Cycle | Spring spawning, summer growing in mud ponds, repeated selection, autumn harvest (ikeage) |
| Selection | Only a small fraction of each spawning is kept at each selection round |
Production in Ojiya follows the mud-pond year. Parent fish spawn in spring; fry grow through summer in nutrient-rich mud ponds; breeders select repeatedly, keeping a small fraction each time; and in autumn the ponds are pulled in the harvest called ikeage, when the year's fish are sorted, assessed and photographed for sale and shows.
The system explains two visitor observations. First, why so many young fish look unremarkable: pattern refines with growth, and selection is a multi-year filter. Second, why autumn is the region's dramatic season: harvest days concentrate the year's work into net-by-net judgements.
This page describes the system as published fact. It does not list individual breeders, quote stock or prices, or reproduce breeders' promotional material — those are excluded by this site's scope.
Sources: Wikipedia (CC BY-SA — summary in our own words, credit only); All Japan Nishikigoi Promotion Association official; Ministry of Agriculture, Forestry and Fisheries (MAFF) and Finance Ministry trade statistics as published; Japanese Agricultural Standard (JAS) for nishikigoi variety names and definitions (2022); Niigata Prefecture, Ojiya City, Nagaoka City (Yamakoshi) and Nishikigoi no Sato official; Japan National Tourism Organization (JNTO) visitor statistics; USDA APHIS and Australian DAFF official import guidance. Checked 6 November 2026.