Ayu : Sweetfish 

Sweets from the river

Japanese anglers’ best-loved river fish are the iwana char, yamame freshwater salmon and ayu sweetfish. The iwana inhabits the narrow, upper reaches of mountainous clear rivers, followed by yamame where the river widens, and the deepest-water dwelling ayu.

The iwana is found only in Hokkaido, Honshu and Shikoku not in Kyushu. It is called ‘rock-fish’ after the boulder-strewn riverscapes it inhabits. As tasty as yamame, it is best in late spring and early summer. It is fantastic as shioyaki, served with sansho. It can also be served as kara'age dusted in flour and deep-fried and kanro-ni, a sweetened simmered dish similar to tsukudani, using glutinous starch syrup.

Ayu no Shioyaki on sale at the Setsubun Festival, Mt. Yoshida, Kyoto.  
Ayu no Shioyaki on sale at the Setsubun Festival, Mt. Yoshida, Kyoto.

Photograph by John Einarsen, courtesy of Kyoto Journal

Yamame means ‘mountain girl’. It is a beautifully marked freshwater version of both the saltwater sakura-masu cherry salmon or the biwa-masu identified by two red spots on its body. Around 30cm in length, it is in season from early summer to autumn. Often it is just plainly grilled without salt and dipped in shoyu.

The pick of Japanese river fish however must be the ayu. Sweetfish spawn in the autumn so taste best as they fatten up during the hot summer months. The strongest tasting, almost pungent fish are the wakaayu young ayu taken from start of May to the beginning of the summer. The komochiayu of the autumn, containing roe, are also good. Lake Biwa in Shiga prefecture and the Nakagawa River that flows through Tochigi and Ibaragi prefectures are renowned for the quality of their ayu.

Gourmets savour the taste of the bitter konowata intestines of the fish, a result of wild sweetfish feeding on freshwater algae that retains its smell in the entrails of the fish. It's a strong, bitter, riverine flavour that takes a little getting used to. A little sake on the side helps! You can eat the whole fish, head, guts and all. I always d

Farmed fish can be bought all year round. Country folk distinguish natural ayu from cultivated fish by their longer, pointy chins needed to root out riverbed algae. They are slimmer, a pale green, and have an orange hue to the tail. The domesticated, hand-fed versions have rounded chins and are fatter and darker in tone. Aichi, Wakayama and Tokushima prefectures are centers of production.

The Japanese character for ayu 鮎consists of two elements, ‘sakana’ fish and ‘uranai’ meaning ‘fortune telling’. This bizarre nomenclature originates in Japan’s distant past when the mythical Empress Jingu, en route for Korea, caught an ayu on Tamashima, in Matsuura. The Empress decided this was auspicious, and that Korea would be defeated. History doesn’t record whether the fortune-telling fish was right.

When to eat

Any time between May and the autumn.

Where to eat

During the summer months impromptu riverside restaurants pop up around the country to serve grilled freshly caught sweetfish. The ancient practice of using cormorants to catch and, yes, regurgitate ayu is a tourist favorite in Kyoto's Arashiyama district, and on the Nagaragawa River in Gifu prefecture.

FGL recommends

Ayu salted and grilled shioyaki, especially with water pepper vinegar, tempura or furai, and as sushi, especially ayu no sugata-zushi. If you are feeling especially bold, try the shiokara-like shibu uruka ayu guts and eggs mixed into a salted paste, or mako uruka just the eggs.

FGL Healthwatch

Ayu contain calcium, vitamin A, D, phosphorus, EPA and DHA, and, in the guts, Vitamin B. Said to posses immune-boosting, anti-infection, anti-ageing, anti-osteoporosis and blood cleansing qualities. Also anti-thrombotic, anti-clotting, and prevents or alleviates arteriosclerosis and anemia. Relieves anxiety and stress. Good for tired eyes.

A shorter version of this article by John Ashburne originally appeared in World Food Japan, published by Lonely Planet. FGL is grateful for the publisher's generosity in allowing us to revisit the material. For more writing on food and Japan visit Lonely Planet - Japan.

John F. Ashburne

John F. Ashburne

Editor-in-Chief Foodies Go Local