Two grow-out experiments were conducted to evaluate the functional role of chicken manure for Nile tilapia. Oreochromis niloticus (L.), production in central Thailand. Experiment 1 examined the relationship between chicken manure input and net fish yield (NFY). Experiment 2 determined the value of chicken manure in providing tilapia particulate organic carbon, and/or dissolved inorganic carbon (DIC) for stimulating algal productivity. in both experiments supplemental urea and triple superphosphate (TSP) gave all treatments total nitrogen (N) and phosphorous (P) inputs of 28-0kg/ha/week and 7-0kg/ha/week, respectively. Addition of chicken manure to inorganic fertilization did not enhance production of Nile tilapia. NFY in experiment 1 increased with decreasing manure loading, which corresponded to increasing TSP input. Regression analysis suggested that chicken manure-P was about 10% effective as TSP-P at increasing NFY. NFY was linearly correlated to total alkalinity. Treatment differences in alkalinity, community respiration, or dissolved oxygen concentrations at dawn were not related to manure input. Simple economic comparisons discourage the purchase of chicken manure as a source of soluble N and P for increasing algal productivity in Thailand.