The objective of this study was to analyze the trophic ecology of Hemiodus unimaculatus, Hemiodus argenteus and Hemiodus gracilis, through the determination of food content and bromatological evaluation beyond the reproductive period if the H. argenteus e H. gracilis according to seasonal variations in a floodplain lake located in Lower Tapajós, Pará, Brazil. Samples were taken from October 2016 to June 2018, totaling 21 months of collection. For the analysis of the diets the frequency of occurrence (FO%) and Relative Volume (V%) of food items, combined in the calculation of the Food Index (%IAi), were verified. Feed intensity was represented by the Repletion Index (IR). The amplitude of the trophic niche was calculated using the Levins measure and the diet overlap was estimated using the Pianka Index. The food strategy was defined using the Costello graphical method. The heat map was used to understand the changes in the trophic structure and the patterns in the seasonal variation of the species studied. The reproductive aspects were evaluated through RGS, weight-length and gonadal condition factor, these were combined with the bromatological analyzes to verify possible relationships between the parameters. The three species consumed a diverse number of food items, composed of phytoplankton, microcrustaceans, insect eggs and larvae of Chironomidae and which are found mainly adhered to the roots of macrophytes and detritus and which was intensified mainly during the dry lake. The three species intensified feeding during the lake’s drought ebb. H. gracilis was the one that presented the most heterogeneous diet, this species had greater amplitude of niche, when compared to the other two species; however, the food items were consumed in small quantities and therefore the niche amplitude showed a result whit the narrow niche. The overlap of the diets was high in all periods analyzed. Costello’s graph showed that species are generalists within the trophic category of detritus. The heat map showed the formation of the groups of the species and the food items, and how the overlap of the diets adjusts according to the seasonal variation. Quando aos aspectos reprodutivos para Hemiodus gracilis and Hemiodus argenteus, females predominated in relation to males (2.5:1 and 1.7:1 respectively). The weight-length relation indicated negative allometry for H. gracilis for sex together, females and males and positive allometry for H. argenteus for clustered sex and females, and negative for males. The analysis of the reproductive period of H. gracilis and H. argenteus showed that the species used the environment mainly as a nursery area, The bromatological analyzes for H. argenteus did not present a strong correlation with the reproductive parameters, whereas for H. gracilis it had a strong relation with the reproduction of the individuals. The composicion bromatological for H. argenteus the moisture analysis presented a mean of 79.0 ±2.5, ashes of 5.0% ±0.3, protein of 16.7% ±3.0 and lipids 4.7% ±1.4. In H. gracilis the humidity averages 77.9% ±3.1, ashes of 4.5% ±0.6, protein of 17.4% ±2.5 and lipids of 3.7% ±0.4. The three species use the lake as a place of feeding, nutrition, growth and reproduction. Showing the important to emphasize the need to preserve this ecosystem to keep the fauna e flora conserved.