Effects of phosphorus and nitrogen fertilizers on the abundance of fish food organisms were investigated in four newly excavated ponds. Before fertilization the ponds were characterized by low nitrogen and phosphorus concentrations, pH values near neutrality, low total alkalinities, and dissolved oxygen concentrations near saturation. After fertilizers were added to three ponds, chemical and physical conditions were altered considerably by the production of large quantities of plankton organisms. Establishment of plankton populations was followed by development of benthic communities, especially in the two ponds receiving both nitrogen and phosphorus. The benthic community developed most rapidly, and the biomass became greatest in the pond receiving the heaviest applications of nitrogen and phosphorus. In ponds which received no phosphorus, benthic production was low.