In season from late spring all the way through to autumn, Ayu (アユ/鮎), Plecoglossus altivelis, or sweetfish in English, is probably Japan’s most famed freshwater fish. Praised for its refreshing taste that people tend to associate with cucumbers and melons, the taste of Ayu is like a breath of summer air, or like a freshly poured glass of Marlborough sauvignon blanc. This is because unlike most other freshwater fish you’d find elsewhere, Ayu feed solely on the moss that grows on rocks in extremely clean rivers, and thus does not have the usual muddy taste that you’ll associate with other freshwater fish like carp. Just like how wasabi is extremely sensitive to pollutants in the water, Ayu is similar in the way that it is also a testament to the extremely untouched rivers of Japan as rivers that are contaminated with impurities due to human activity quickly lose their Ayu population.
Just like most fishes in Japan such as wild eel (unagi), the prices of wild Ayu is ever increasing, which has driven consumers to move towards farmed products. In fact, a lot of Ayu farms exist outside Japan in Taiwan and are imported back into Japan. Just like Japanese eel, Ayu is an amphidromous fish, which means the eggs hatch in the ocean during the winter but return upstream to the rivers to live for the rest of the year during the start of summer. In fact, Ayu fish lay their eggs in the fresh waters at the bottom of the rivers in pits, with the baby Ayu being washed into the ocean by the river current. This is why the season for Ayu starts during late spring or early summer, because it is then that angler’s start catching them in rivers around Japan. There are of course, landlocked populations of Ayu that seem to have evolved the ability to spawn in freshwater, such as the Ayu population in Lake Biwa (琵琶湖). I might be mistaken about this, but the amphidromous population of Ayu tend to only spawn once before dying, therefore living for only a year, whilst the landlocked populations of Ayu tend to live up to 2 to 3 years.
The most interesting aspect of Ayu is probably the way they are caught, using a method known as Ayu no Tomozuri (鮎の友釣り). Being highly territorial fish, wild Ayu will attack any other fish that enter its territory, including fellow Ayu fish. By using a live Ayu as bait, fishermen attach hooks to the live Ayu and cast the Ayu at the end of the line to trigger the other Ayu to attack the bait, thus allowing you to use 1 Ayu to catch another. Another method of catching Ayu is through cormorant fishing, alright this method is now more of a tourist attraction rather than a commercially viable method.
Similar to Kohada, the name of the fish varies with age, with young Ayu being known as Waka-Ayu (若鮎) which is renown for having the strong taste of cucumber and melons. Waka-Ayu is also the name of a much more famous Japanese confectionary in the shape of an Ayu fish. Ayu that have survived through to autumn and are fat with roe are known as Komochi-Ayu (子持ち鮎) and whilst are less pungent have a richer, fattier taste.
Ayu is typically served in Kaiseki Ryori restaurants rather than sushi restaurants, and are typically salt-grilled. Unlike salt-water fish that are gutted and cleaned however, Ayu is typically eaten whole, including all the innards and gills. In fact, the bitter taste of the innards are highly prized as they balance out the sweet and refreshing taste of Ayu. The term of this taste is konowata (このわた). When skewered to be grilled over charcoal, the fins of the Ayu are salted to allow them to stand up, whilst the skewer goes through the body in an in and out fashion to make the fish seem as though it is “lively swimming”.
Being the prefectural fish of Gifu Prefecture (岐阜県), this recipe covers a classic recipe that Gifu is famous for- Ayu Gohan (鮎ご飯).
- Skewer the Ayu as shown in the picture above, otherwise, directly grilling the Ayu is also alright as we won’t be serving the Ayu whole and so presentation does not matter as much.
- You can either grill it over charcoal or grill in an oven at 200°C for around 5 minutes each side or until the skill is nice and golden brown. You do not need to fully cook the fish as the fish will continue cooking in the rice pot.
- If the Ayu are large, trim away the fins, including the tail fin, and discard as they can be hard to eat. You might want to do this for smaller Ayu as well.
- Cut off the heads of the fishes and using a tweezers, you should be able to pull out the spine of the fish through the opening revealed from cutting off the head.
- Place the heads and spines back on a wire-mesh/tray and grill them again crunchy.
- Add the heads and spines to the dashi in a saucepan, bring to a boil before turning off the heat and allowing to rest for 5 minutes.
- Place the rice, sake, soy sauce in a donabe rice cooker, before straining out the dashi to remove the heads and bones and adding the stock to the donabe.
- Gently mix to combine the seasoning and rice.
- Add the sweet pea shoots on top of the rice.
- Place the fish on top of the sweet peat shoots, and close the lid and cook according to your donabes rice cooking instructions. You can find instructions on cooking rice for donabes here and here.
- Once done, remove the lid of the donabe, add in finely chopped ginger and spring onions to taste, and mix in the Ayu meat with the rice, breaking apart the Ayu meat as you mix. By both grilling and steaming the Ayu, the small bones remaining in the Ayu should be soft and edible, especially since the spines have been removed. If you are worried about bones, remove the Ayu from the donabe onto a plate and break up the flesh with a spoon and fork, removing any bones along the way before re-adding the meat to the rice and mixing together.
For this recipe I leave in the innards of the fish but if you do not enjoy the bitter taste feel free to remove them.
The addition of Sweet Pea Sprouts, Tomyo is not a typical addition to this recipe and is optional or can be substituted with any vegetable of your choice.
If fact, the most basic version of this dish you get in Japan has only the fish, rice, and seasoning with ginger, excluding any vegetables or spring onions.
If using a rice cooker just follow the same instructions for cooking rice as you typically would for white rice.
This recipe was made in the rice cooker donabe by Kumoi Kiln and was inspired by a meal served by Kiyofumi Kozuru at his traditional open hearth (Irori/囲炉裏) restaurant Tadenoha (たでの葉) in Aoyama, Tokyo in the exact same claypot. More information about the restaurant can be found here and here and here.