The authors are grateful to the crew of Mikuni-maru and Mr. Takuma Shigeno for their effort in providing live fish samples. We are indebted to Dr. Tomohito Imaizumi and Dr. Tomohiko Matsuura of NRIFE for providing support in measuring the irradiance of the LED device. We especially thank Dr. Yukimasa Ishida for reviewing the draft. We are also grateful to Dr. Satoshi Katayama of Tohoku University for his helpful comments. We appreciate the valuable sug- gestions from three anonymous reviewers in improving the manuscript.