Digestive physiology of fish larvae during ontogenic development: A brief overview

The knowledge of digestive physiology of fish larvae is the most crucial for the development of proper feeding strategies to fulfill their nutritional requirements. The yolk sac exhaustion, mouth opening and food consumption should be synchronized in such a way that the consumed food will be digested efficiently resulting higher survival and growth of larvae. This review focuses on thc morpho-functional changes occuring the digestive system of fish during ontogenic development. Mouth gape plays important role in larval feeding. Development and regulatin of the digestive enzymes depend on the progressive changes in the digestive tract. This is either genetically programmed or induced by the corresponding substrate in the food. Protease and lipase activities show variations during the shifting phase of feeding. Trypsin and chymotryspin play a major role among the serine proteases in the early development in all cyprinids. which lack a true stomach. The activity of these proteases is associated with pancreatic secretions. The pronounced amylase activity in some fish at the first feeding suggests the importance of carbohydrate metabolism in ontogeny of these species. Microorganism play important role in digestion. The morpho-functional changes of digestive system during ontogenesis influcuce the gut evacuation rate. This information will be useful for the formulation of artilicial feed for fish larvae.