PACKING BOXES AND CONTAINERS OF DENATURED FISH

All packing boxes and containers containing denatured fish shall bear thereon in a conspicuous manner in bold face type not less than one-half inch in height the statement "for animal food only." Such statement shall be printed or form a part of the main label affixed to or stamped on such packing boxes or containers or shall be stamped on the same end or side of such packing boxes or containers that such main label is affixed or stamped thereon.