When you go to the market, you often find leftover fish scraps bundled together and sold cheaply.
While they might not look great, they're convenient for dishes like hot pots.
One day, I suddenly decided to try making Saikyo-zuke (Kyoto-style miso-marinated fish), so I made two types: one based on a recipe, and another with nuka (rice bran) I had on hand, based on my own whim.
The meal was delicious, but salty.
The fillets were quite thin, so I should have kept the seasoning milder (naturally).
I wonder if even pickled fish like this, known as a delicacy with complex umami, was originally intended to preserve food for an extra day or two.