This year, the number of Ayu running up the river was much higher than in recent years, and the number of Ayu that come down the stream seems to have been very high. This year, the mountains were saturated by the long rains during the summer, which kept the water flowing and improved the water quality, which may have had a favorable effect on the growth of Ayu. The photo was taken from the river bank near Katsura Imperial Palace, showing Ayu fish swarming in the water. Ayu fish are much larger than other fish such as Oikawa, a pale chub, (Zacco platypus) and they are swarming together or in groups of four or five. You can often see them jumping in the shallows nearby. They may be spawning.
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Photo 2021-10-15