To understand the ecological relevance of fish-forest interactions, we sampled fish for a period of 8 months in a lowland forest of the Brazilian Amazon and evaluated the germination of intact seeds recovered from the intestine of three species of congeneric and sympatric freshwater sardines, Triportheus albus, T. angulatus and T. auritus. The number of seeds consumed by the three fish species and the possible effect of individual fish size on seed germination were investigated. We captured 150 individual sardines, of which N = 59, contained 982 intact seeds from seven flooded forest tree species. All the seeds were already pulped due to the digestive process and were sown to check its germination rates. We selected two pioneer tree species, Cecropia latiloba and Laetia corymbulosa, which were the two most consumed seeds to analyze the effects of its passage through the fishes’ digestory tracts on seed germination rates and speed, compared to intact seeds directly collected from trees (control). Seeds harvested from the wild were not scarified or scrapep to remove the pulp because of the large amount of diminutive seeds of the two pioneer tree species. Fish body size did not affect the probability of germination of the consumed seeds of C. latiloba or L. corymbulosa. For both plant species, there was a reduction in the probability of germination of seeds taken from the intestine of fish in relation to control seeds collected in nature. Control seeds also germinated faster than those consumed by fish. Despite the seemingly negative effects on germination rates and speed after passing through the digestory tracts of the freshwater sardines, the fishes' ability to transport seeds away from the parent plants can compensate for the loss of viability of some of the ingested seeds, especially when the proportion of viable seeds remains high.