Inositol is usually classified as an essential vitamin for most animals, and is recognised as a part of the B-complex vitamins. Among all other inositol isomer forms, myo-inositol possesses biological activity. It is found in the brain, skeletal, heart, and main reproductive tissues and exists as a structural component of phosphatidylinositol in biological cell membranes. Myo-inositol, also acts as a growth factor and affects the antioxidant capacity and oxidative status of cells. It is a major intracellular osmolyte that can be accumulated to protect cells from a variety of stresses and can also participate in transmembrane signal transfer. Myo-inositol is synthesised by various animal tissues and microorganisms in gut and fulfils the requirement for a few fish species. However, the supply of inositol by exogenous source (the diet) is required in most fish and shrimp for preventing deficiency signs such as inefficiency in digestion and food utilization, poor growth, fin erosion, dark skin colouration, and high accumulation of lipid in liver and muscle. The current paper aimed to provide a review on the published studies on the role of inositol in aquaculture.