Objectives Aquaculture farmers were guided to better and efficiently utilize betaine to improve the efficiency of aquaculture. Methods The biological functions of betaine and its application in aquaculture were summarized by reviewing relevant literature. Results Betaine is a quaternary amine alkaloid with functions including transmethylation, antioxidation, regulating osmotic pressure, and improving lipid metabolism. Betaine can promote the growth of aquatic animals, improve meat quality, and enhance stress resistance in the production of aquaculture. It has been widely used in the production of aquaculture. Conclusions Betaine, as a feed additive, plays a significant role in aquaculture, but its biological mechanisms and applications are still in the primary stage. Further exploration and studies are needed to achieve its efficient utilization.