The food of a fresh-water goby, Rhinogobius similis GILL, was studied in the River Ukawa during the summer and the autumn of 1958,with the following results. This fish is able to feed on the bottom insects as well as on the algae, and the stomach contents change in accordance not only with the composition and amount of food substances but also with the abundancy of the dominant fish, Plecoglossus altivelis, in the habitats. The amount of insects taken by female adults of 6.5〜8.5cm in total length was estimated to be about 0.1 gramme(wet weight)per day, when fed exclusively on the bottom insects in July.
