There is provided a method for preventing the occurrence of abnormal behavior such as cannibalism, fright behavior and collision death during rearing, storage and transportation of tuna of larva, juvenile and young adult fish stages, particularly, of those periods in the seed production. The abnormal behavior during rearing, storage or transportation of tuna is prevented by controlling their visual stimuli, particularly, by making wall and bottom surfaces of a rearing water tank coming with contact with the environment transparent, setting a visual stimulus-buffering material through which light transmits partially in both straight and diagonal directions, maintaining the tuna in the presence of colored fine particles in the environment, or controlling the fluctuation in illumination of the environment, or a combination thereof. Alternatively, death of tuna due to collision with a rearing water tank wall is prevented by stimulating their visual sense.本發明提供一種防止仔魚期(larva)、幼魚期(juvenile)及早期成魚期的鮪魚,尤其係種苗生產時期的鮪魚,在培育、貯存及運送期間發生諸如同類相殘、驚嚇行為及碰撞死亡之不正常行為的方法。藉由控制鮪魚的視覺刺激以防止鮪魚在培育、貯藏或運送期間的不正常行為,特定言之,係藉由下列方法進行:使與環境接觸之培育水槽的壁面及底面透明化;設置視覺刺激緩衝材料,使透過該材料之光線部分地以直向及斜向二個方向來傳送;使鮪魚在彩色微粒存在的環境中;或控制環境照度之不規則變動;或者上述方法之組合。或者,藉由刺激鮪魚的視覺以防止鮪魚碰撞培育水槽壁所造成的死亡。
