<；P>；PROBLEM TO BE SOLVED: To provide a method for sex manipulation in fishes, particularly promoting feminization in manipulating sex in fishes. <；P>；SOLUTION: In the method for sex manipulation in fishes performing the sex manipulation of fishes, solely a red-color light having a maximum wave length W in a range of 600 nm&le；W out of wave lengths W of lights is irradiated for a predetermined period of time inside of a living area of the fishes at least before determining male or female of the fishes, wherein the predetermined period of time is brought to be 30-100 age in days after hatching of the fishes, and water temperature inside of the living area of the fishes is brought to be equal to 18°；C or lower, preferably 14°；C or lower. <；P>；COPYRIGHT: (C)2009,JPO&INPIT
