Modelling the growth of Nile Tilapia (Oreochromis niloticus) feeding on natural resources in enclosures in Laguna de Bay (Philippines)

Laguna de Bay (Philippines), one of the largest freshwater bodies in the So utheast Asia, is located near Metro Manila. The lake is an important resour ce for the local population because of fish production: fishing and aquacul ture are relevant activities for the economy of the area. Nile Tilapia (Ore ochromis niloticus) is one of the cultured species and it is grown within n et cages in the lake. In this paper, a model is proposed to describe the gr owth of Nile Tilapia under natural conditions; food sources have been consi dered to be phytoplankton, zooplankton and suspended organic matter (detrit us), without additional feed supply. The metabolic approach has been adopte d to describe fish growth. The parameters characterising fish metabolism ha ve been estimated for O. niloticus or similar species, according to literat ure information. The model has been applied to twelve growing conditions re presentative of increasing stocking densities and of different growing peri ods. Model results have been successfully compared with the experimental da ta reported in literature. This model has been used to estimate the amount of natural food (phytoplankton) exploited by the culture of O. niloticus wi th the final aim to quantitatively relate lake's water quality with fish gr owth and production. (C) 1999 Elsevier Science B.V. All rights reserved.