What is Kohada コハダ 【小鰭】?
In Japanese, Kohada stands for a medium-sized dotted gizzard shad (konoshiro, コノシロ) which belongs to the herring family. Kohada is considered a classic ingredient of edomae sushi and is especially popular in East Asia.
A fish that changes its name
Kohada belongs in Japan to the “rising or ascending fishes” (shusseuo), this refers to fishes that change their name depending on size and age. A dotted gizzard shad carries the name Sshinko up to about 5 cm total length, from a size of 7 to 10 cm it is called kohada. As soon as it reaches 13 cm, it carries the name nakazumi, in order to then be called konoshiro as adult fish from a length of 15 cm. For the preparation of a nigiri sushi, depending on the size of the fish, either whole or multiple specimens of the size shinko are used.
If you look at the growth in value of the konoshiro, you can almost mockingly claim that it is a “descending fish”, because with increasing size its value and thus its selling price decreases. Especially for the preparation of sushi, smaller sizes like kohada or shinko are appreciated.
Kohada for Sushi and Sashimi
Kohada is not only a popular ingredient for the preparation of sushi or sashimi, it is also a symbol for the philosophy of Edomae sushi among connoisseurs and chefs alike. Because of its fresh, shiny appearance (hikari-mono), it is considered one of the most beautiful sushi dishes, which reaches its peak in flavor only when properly prepared and combined with sushi rice.
Kohada is the cheapest fish among all sushi neta (sushi ingredients, typically fish), but if you prep it well, it turns into the “Yokozuna of Nigiri”. Jiro Ono in Sushi Chef: Sukiyabashi Jiro (Satomi, 2016)
When the meat of kohada is salted and marinated in vinegar (sujime-method), an exceptionally full-bodied taste is created, which harmonizes wonderfully with the subtle sweetness of sushi rice. In addition, the marinating process reduces the strong taste and softens any bones that may still be present. The duration of application and dosage of salt and vinegar are adjusted according to the size of the fish, the amount of fat and the season, so that a lot of experience in preparation is required. Hardly any other fish can vary so much in taste by treatment with salt and vinegar, so it is said that kohada is a measure of the chef's skill or the quality of a sushi restaurant. Depending on the size of the fish, either the whole fish can be used or up to four whole specimens of the size shinko.
The taste of kohada sushi is characterized by mineral aromas accompanied by a buttery sweetness and subtle acidity. The range of possible side dishes or garnishes is wide and ranges from crystallized egg yolk (kimi-oboro) or shrimp paste (oboro) over citrus fruit (yuzu) to a refined soy-mirin sauce (nikiri). Besides its wonderful taste, the meat is rich in proteins, essential fatty acids and trace elements.
The spawning season begins in early spring and ends in early summer, with some fish spawning twice or more (Takita, 1978). The season for small fish named shinko starts in July and ends in August. Medium sized specimens with the name kohada are mostly caught between August and September. Large specimens of the konoshiro are caught all year round, but are most palatable in the winter period from November to February.
Characteristics & Ecology
The distribution area extends along the coast of the Japanese archipelago over the Korean peninsula to the East China Sea. The dotted gizzard shad is only slightly migratory and does not change its habitat significantly during its life cycle. Its diet consists mainly of plankton, diatoms and small crustaceans.
Konoshiro is only of minor economic importance. According to the Food and Agriculture Organization of the United Nations (FAO), Japan is the only country that fishes Konoshiro in industrially relevant quantities. Since 2005, South Korea has been producing Konoshiro from aquaculture.