Nutrient budget analysis in carp based polyculture ponds

Nutrient enrichment of pond waters is an essential management practice in aquaculture (Boyd, 1990; Pillay, 1999). Intensification in aquaculture through the high stocking density and inputs in ponds not only results in increased fish yields, but also improves efficiency in land use and water consumption. However, the most concerned problem resulted from the intensive aquaculture is waste effluents which contain highly concentrated nutrients, organic matter and suspended solids. The discharge of this nutrient-rich water, an environmental regulatory concern in many developed countries, may result in the deteriorated quality of receiving waters (Yi et al., 2003). Thus, nutrient budget analysis is necessary for any new aquaculture system before it is recommended to farmers. The nutrient-budget analysis is generally used to assess the relationships between feed nutrients input, nutrient retention in the cultured fish, and nutrient release to the environment in relation to a given production (Gowen et al., 1988).