Morphological Changes Of Marine Fish Larvae And Their Nutrition Need

Fish larvae represent a critical period in their life history because during ontogenetic development, important changes in structure and function occur in body tissues, organs and systems. Fish larval nutrition starts from an endogenous origin where larvae derive nutrition from yolk reserves and subsequently develop into exogenous feeding. In the early feeding stage, fish experience mixed nutrition during the transitional period from endogenous to exogenous nutrition. In mixed feeding, nutrition supply plays an important role in fish survival. Therefore, an understanding of the structural and functional changes of the larval digestive system is essential to select appropriate feed to improve fish survival in larval rearing. In aquaculture, high fish mortality usually occurs in the early stage that coincides with the period of initial exogenous feeding. Specifically, the timing of food introduction is critical because food ingestion in first-feeding larvae determines subsequent fish survival and growth. In this chapter, we use the life cycle of larval fish as a framework to examine internal factors regulating ontogenetic development in fish larvae and environmental factors contributing to fish mortality during early life history.