Vitamin C comprises a group of related water-soluble substances that are crucial to the physiology and health of aquatic animals. Most aquatic animals have a limited capacity to synthesize Vitamin C, thus obtaining Vitamin C predominantly from diets. Because of its ability to scavenge free radicals, act as an antioxidant, and reduce inflammation, vitamin C has become increasingly popular as an ingredient for aquatic feed in recent years. However, the amount of vitamin C that various aquatic organisms require differs substantially from one another. This updated review presents a general outline of the possible physiological function of vitamin C for farmed aquatic animals, with an emphasis on the information on growth, antioxidant status, immunity, disease prevention, and reproductive performance, as well as the synergistic effects of vitamin C with other micronutrients such as vitamin E, glucans, and metal elements during the past few years. In addition, the interaction between the gut microbiota of aquatic animals and the dietary vitamin C that they consume is something that has been looked into. When it comes to expanding the use of vitamin C in the aquaculture industry, having a solid understanding of the positive functions and mechanisms that vitamin C possesses is of the utmost significance.