Feeding experiments on juveniles of the freshwater pearl mussel Hyriopsis schlegeli were conducted using upwelling chambers. Growth of juveniles mainly fed with a mixture of two green algae, Chlorella homosphaera and C. vulgaris, in 2013, was compared with that of specimens fed only with C. vulgaris in 2012. Juveniles in 2013 grew much faster than those in 2012 and their mean shell length exceeded 20 mm, achieving record maximum size. The result implied that using upwelling chambers and feeding small green algae are effective for successful culture of H. schlegeli.