Tilapia nilotica and shrimps of the Macrobrachium species, separately and in combination, were stocked, in 15 0.1 ha fertilized earth ponds. Yield of T. nilotica in ponds stocked with 5 kg/ha adult shrimps increased by 21 % over that of ponds with T. nilotica only. Presence of the shrimps also increased the total yield of polycult'ure ponds by 22% compared to that of monoculture ponds with T. nilotica alone. The shrimps apparently contributed substantially to the natural diet of T. nilotica. Adult shrimps stocked at 5 kg/ha yielded more than juveniles stocked at 10 kg/ha in monoculture and polyculture ponds.
Culture of Tilapia nilolica in freshwater ponds is gaining wide acceptance in the Philippines. Experimentally, the monoculture of the species in fertilized fishponds at 10,000 to 20,000/ha has given yields of 612 to 1,100 kg/ha respectively (Guerrero, 1976).
Two freshwater shrimp species, Macrobrachium lanckesteri and M. lanceifrons montalbanense, were found to be capable of reproducing in fishponds (Guerrero, Guerrero and Grover, 1975). Preliminary studies on the monoculture of shrimps and in combination with Tilapia mossambica and T. nilotica had encouraging results (Guerrero and Guerrero, 1976).