The culture of different fish species with different food habits in a pond at the same time thus making most efficient use of the culture environment is one way to increase fish production. Different species of carp, for example, show particular promise for use in such polyculture system. This experiment in the newly constructed ponds at the Freshwater Aquaculture Center was designed to find out what production could be expected from combined carp culture in ponds with and without the use of fertilizer. Such information should be useful in predicting yields and guiding management pratices like stocking rate, length of culture and effectiveness of fertilizers. This experiment combined the planktoon-feeding silver carp, Hypophtalmichthys molitrix; the omnivorous and benthos-feeding common carp, Cyprinus carpio; and the herbivorous rohu carp, Labeo robita.