Hikari Koi Food. Hikari Koi Fish Food - Japan's Best. Hikari Koi Food is by far the most popular koi fish food in Japan and is considered the standard by which other foods are measured. Hikari has researched, developed and produced many types of koi food in their facility for over 130 years. They breed fish in their own facilities and observe the impact of their diets over time. Hikari's state of the art research laboratory is unmatched world wide.