PROBLEM TO BE SOLVED: To provide a production method of fish, a growth promotion method of fry, and a growth promotant of fish, promoting the growth of fry by a simple procedure.SOLUTION: A production method of fish includes: an aqueous solution preparation step of preparing a first aqueous solution containing L-sodium lactate, sodium chloride, potassium chloride and calcium chloride; a plasma irradiation step of irradiating the first aqueous solution with atmospheric pressure plasma using a plasma generator P1 to make a second aqueous solution; and a fry raising step of raising fry by adding the second aqueous solution to raising water. The second aqueous solution is a growth agent for promoting the growth of fry.SELECTED DRAWING: Figure 1