<；P>；PROBLEM TO BE SOLVED: To provide a rearing, storing or transporting method for tuna effective for economically surviving an immature tuna for a long time, a method for preventing startle response of tuna and a method for enhancing appetite of tuna. <；P>；SOLUTION: A swimming tank 10 for immature tunas is produced by extending a sheet material in a top-opened and bottom-closed cylindrical form. Four illumination devices 20 for lighting inside of the swimming tank 10 are placed above the swimming tank 10. The illumination devices 20 include light projectors capable of projecting light over a wide area at a uniform illumination intensity, and arranged almost uniformly along the circumferential direction of the swimming tank 10 to illuminate the water surface of the swimming tank 10 at nearly uniform illumination intensity. The illumination devices 20 are placed in directions to project light against the inner wall of the swimming tank 10 to allow easy recognition of the wall surface by the immature tuna. The water surface of the swimming tank 10 is kept to an illumination intensity of &ge；1,000 lx in the daytime and is almost uniformly kept to an illumination intensity of about 10 lx at night. <；P>；COPYRIGHT: (C)2011,JPO&INPIT
