Vitamin C phosphate (L-ascorbic acid-2-phosphate) is produced by introducing a phosphate protective group at the 2-position of ordinary vitamin C; once ingested by animals, it releases active VC via enzymatic hydrolysis by phosphatase, fundamentally solving at the molecular level the longstanding issue of ordinary VC being prone to oxidation and losing efficacy during feed processing and storage. The mainstream active content of feed-grade products is 35% (with 25% and 40% grades also available), offering excellent heat resistance, storage stability, and water stability, making it the most stable vitamin C source currently used in aquatic extruded and pelleted feeds, with bioavailability equivalent to equimolar VC. It is widely applied for anti-stress, immune enhancement, growth promotion, and liver protection/detoxification in fish, shrimp, and crabs, and is also suitable for anti-stress use in livestock and poultry as well as for premix addition.