Information on food, feeding rhythm and daily ration of fish are useful to evaluate the relationship between growth and feeding, predation pressure, competition, and seasonal food limitation. This type of information was lacking to Cichla monoculus in its natural habitats in the Central Amazon floodplain and here it is presented data on the feeding ecology of this species during one hydrological cycle. The study included three floodplain lakes sampled between August 1997 and July 1998. The diet and feeding rhythm were evaluated with gut content analysis and the gastric evacuation rate was measured experimentally. The daily ration was estimated with Elliot and Persson's model and Egger's model. Feeding intensity was lower during the dry season. The diet consisted basically of fish, comprising 9 families of fish but one family of shrimp occurred in 20% of the samples. The gastric evacuation rate was 16.9%h-1. The daily ration was not different between seasons and averaged 2.23% bw. This is a relatively low value compared to other piscivores.