The present invention is a pretreatment agent for a fish food which comprises, in a mixture, 1 30% (v/v) of ethanol, 5 25% (w/v) of citrate and 0.5 50% (w/v) of at least one inorganic salt selected from the group consisting of phosphate, carbonate and bicarbonate, and a process for pretreating a fish food which comprises contacting the pretreatment agent with the fish food.