Curcumin, an orange-yellow polyphenolic and hydrophobic phytochemical component of turmeric herb (Curcuma longa Linn.), has been recognized as a powerful immunomodulator in both animals and humans. Nanotechnology, a new scientific research field, is broadly utilized in medical sciences; however, it currently has limited applications in fish nutrition. Many studies have demonstrated the beneficial impacts of curcumin and its nanoparticles when used as pharmaceutical agents in animal nutrition. Curcumin has substantial pharmacological and biological properties, such as antioxidant, anti-inflammatory, antimicrobial, chemoprotective, hepatoprotective, anti-cancer, gastroprotective, and neuroprotective properties, and is also involved in growth promotion. Despite the favorable biological functions of curcumin, studies have shown that ingestion of curcumin or its nanoparticles does not benefit animal productivity or health status because of its inferior bioavailability caused by the rapid metabolism and speedy removal of curcumin from the animal body; therefore, advanced formulations of curcumin are required. This review highlights the health benefits and the potential application of curcumin and its nanoparticles in fish nutrition. Moreover, this review offers future perspectives on curcumin and its nanoparticles, and their applications in fish nutrition.