Aquaculture is one of the fastest-growing sectors of food production worldwide, playing a vital role in fulfilling the increasing demand for aquatic protein production. However, infectious diseases remain one of the major concerns for the sustainability of aquaculture production. Conventionally, antibiotics and chemotherapeutics have been used for the control of infectious diseases in cultured aquatic animals. The overuse of antibiotics has led to serious concerns, such as the emergence of antibiotic resistance, environmental contamination, and the presence of residues of antibiotics in fish products. Hence, the use of sustainable and eco-friendly alternatives for the management of infectious diseases has become essential. Probiotics and prebiotics have become important feed additives for improving fish health and production. Probiotics are live microorganisms, which, when administered in sufficient amounts, provide health benefits for the host, while prebiotics are nondigestible components of feed that promote the growth of beneficial microflora in the gastrointestinal tract of animals. Probiotics and prebiotics, as microbial feed additives, have been found to be effective for improving the health of farmed fish. Hence, the use of probiotics and prebiotics can be used as sustainable alternatives for improving the health of farmed fish.