A mechanistic simulation model of fish larval growth should contribute to a better understanding of growth and metabolism of fish larvae. It should also assist in studying the nutritional requirements and developing feeding strategies. A model was developed that simulates growth and biochemical composition in time. The model is driven by feed intake, with absorbed nutrients being used for energy production and biosynthesis, based on the stoicheometry of intermediary metabolism. Model simulations suggest that imbalanced dietary amino acid (AA) profiles and dietary lipid excess may lead to suboptimal growth in fish larvae culture. Tracer studies have therefore been used to study AA and lipid metabolism in fish larvae. In addition, modeling techniques have been also used in these studies, to better interpret results obtained. Digestive capacity, as well as utilization of different AA, fatty acids and lipid classes, has been studied using radiolabeled nutrients (normally with 14C) using a tube-feeding technique. This method allows quantification of the tracer that is present in faeces, retained in tissues and catabolised. Another method, combining the use of live food in which proteins are labeled with a stable isotope and a spectroscopic/spectrometric technique that allows determination of the isotopic enrichment in individual AA, can be used to estimate ideal dietary indispensable AA profiles. Together these two types of techniques that allow the study of nutrient fluxes have lead to important advances in the understanding of fish larvae nutritional physiology and growth.
fish larval nutrition; mechanistic modeling; tracer studies