Matrinchãs (Brycon falcatus) are endemic to the Amazon Basin, and there are few studies on the parasitic fauna of this species, so research that addresses parasite-host interactions is of great relevance. In view of this, collections are being carried out in the Teles Pires River basin to analyze the parasitic fauna of this species as well as its diet. It is known that the study of parasites can provide valuable biological information about their hosts. Among the factors that influence the composition of the parasitic fauna, the feeding habits of the host are one of the characteristics, since they include individuals that play the role of intermediate hosts. Since many parasites are trophically transmitted and have complex life cycles with different hosts, they reflect trophic interactions between organisms. In addition, some fish can be parasitized in both the larval and adult stages and, therefore, exposed to a wide variety of parasite species. Thus, the project aims to contribute to studies of parasitic fauna and evaluate whether diet influences the parasitic diversity of Brycon falcatus.