Phosphorous, nitrogen and carbon have been key limiting nutrients on the forefront of eutrophication literature for more than four decades. Concepts developed by the limnological community regarding these nutrients and their cycles in aquatic environments are now becoming the basis for management of aquaculture systems particularly those in which fertilizers are used to promote fish production. Animal wastes, with a long tradition of use in tropical aquaculture, represent an inexpensive source of organic carbon for detrital production through heterotrophic pathways and soluble nitrogen and phosphorus for primary productivity. Depending on the species, fish will feed directly on attached or planktonic algae, detrital/fungal flocs, or smaller animals such as zooplankton and snails which feed on algae and detritus.