Additive for aquaculture feed for fish and shellfish and aquaculture feed for fish and shellfish which contains same

An additive for aquaculture feed for fish and shellfish, which contains L-ascorbic acid-2-glucoside as an active ingredient, an aquaculture feed for fish and shellfish containing said additive, and an aquaculture feed for fish and shellfish, which has been added with said additive and granulated. The additive for feed of the present invention, namely, L-ascorbic acid-2-glucoside 1) does not have reducing ability by itself, and extremely stable, 2) can be decomposed into L-ascorbic acid and D-glucose when taken in fish and shellfish, and can exhibit physiological effects inherent to L-ascorbic acid, and 3) is greatly improved in heat resistance and light resistance in comparison with L-ascorbic acid, and shows markedly small loss of L-ascorbic acid activity during the production and storage of feed.