This invention relates to a growth promoter for fish and a method for promoting the growth of fish. The growth promoter for fish of the present invention includes a preparation comprising histidine as an active ingredient. The method for promoting the fish growth of the present invention includes a method comprising administering histidine or the growth promoter for fish of the present invention to fish. Fish may be any species. Preferably, it is fish of Carangidae , such as Seriola quinqueradiata and Trachurus japonicus, and Scombridae , such as tuna, bonito and mackerel. Carangidae is more preferable.
