The successful rearing of fish larvae is one of the greatest challenges in modern aquaculture due to the difficulty of delivering essential nutrients and bioactive compounds to the developing digestive system of larvae. Microencapsulated diets have emerged as an innovative approach for improving nutrient stability, reducing leaching losses, and ensuring effective delivery of biologically active substances. This article discusses the role of microencapsulation technology in transporting important bioactive compounds such as hormones, amino acids, and vitamins into fish larvae. Protein-walled microcapsules are designed to retain nutrients in water while remaining digestible to larval fish after ingestion. Studies on gilthead seabream (Sparus aurata) and Senegal sole (Solea senegalensis) demonstrated successful incorporation of estradiol, lysine, and vitamin C into larval tissues through microencapsulated diets. The technology showed high retention efficiency for amino acids and effective delivery of hormones and vitamins, although encapsulation efficiency and growth responses varied among compounds. Microencapsulated feeds also offer advantages such as reduced nutrient wastage, improved water quality, and the possibility of partial replacement of live feeds. However, challenges including nutrient leaching, low incorporation efficiency, and incomplete digestive utilization still limit full commercial application. Despite these limitations, microencapsulation represents a promising strategy for precision larval nutrition and functional feed development in aquaculture. Future advancements in encapsulation techniques may further improve larval growth, survival, immunity, and sustainability in fish hatchery systems.