"Some say that every stream has its own individual scent. Others say fish have a sense of direction, preventing them from becoming lost. Still another opinion claims fish rely on the earth's magnetic force to guide their way home. But there is no real definite answer," concludes Tseng Ch'ing-hsien.
「有人以為每條河有它獨特的味道，鱒魚能記得這熟悉的味道；有人說鱒魚有方位判斷能力，不會迷路；又有人以為它靠地球磁力迴游… …，總之沒有定論」，曾晴賢說這是魚類學家「傷腦筋」已久的問題。