ABSTRACT
Ayu are an anadromous fish that spend most of their 1-year life cycle in fresh water. After spending their first few months of life in the sea, 20 to 30 mm fry enter rivers, feeding on benthic organisms such as diatoms and blue-green algae. After they have reached lengths of up to 25 cm, spawning occurs and the newly hatched fry migrate to sea.
