A preliminary model for dynamic simulation of growth in fish larvae: application to the African catfish (Clarias gariepinus) and turbot (Scophthalmus maximus)

The present study describes an explanatory model that simulates growth and body composition of fish larvae. Its objective is to improve the understanding of the growth process in larval fish, and by doing so, to enable the optimisation of the feeding strategies in larviculture. The model is driven by nutrient intake, with the absorbed dietary nutrients being used for energy production or for biosynthetic processes, and it is based on the stoichiometry of intermediary metabolism. The model was parameterised using literature data and validated for the African catfish and turbot. According to the model, high unavoidable losses of amino acids due to imbalances between the dietary and the larval amino acid profiles lead to an increase in lipid deposition in periods of high food intake. in catfish, this occurs with the contribution of gluconeogenesis. Model simulations indicate that an increase in the dietary protein level of currently used diets would stimulate growth and lead to a reduction in lipid deposition, providing the dietary AA profile is well balanced. An increase of 25% in the dietary protein level may stimulate growth (dry matter) by 15% for the African catfish, and 140% for turbot. Model simulations also show that a 25% increase in dietary lipid level may lead to a small protein-sparing effect, and to an increase of 46 and 36% in larval lipid content for African catfish and turbot, respectively. Due to its mechanistic nature, the present model can be used for other fish species, and in particular in the development of tentative feeding strategies when new species are brought into cultivation. (C) 1998 Elsevier Science B.V. All rights reserved.