Ayu Plecoglossus altivelis of 12cm in body length were raised in concrete tanks at four different water velocities (4cm/s, 25cm/s, 35cm/s, and 45cm/s) for 60 days. Rearing of the fish in water velocities 35 and 45cm/s exerted favorable growth and feed efficiency. Rearing in current water, however, failed to depress lipid content of muscle, liver, and intraperitoneal fat body when com-pared to that in the standing water (4cm/s).
Following the feeding experiment, the fish were starved for 13 days in indoor tanks. The body weight loss was suppressed in the fish reared in water velocities of 35 and 45cm/s. Rearing in high water velocity (<45cm/s) could improve lipid metablolism, especially in activation of utilization of lipid reserves for energy requirements.
In ayu culture, water velocity in the rearing tank should be controlled to 45cm/s or more.
The Japanese Society of Fisheries Science