Purpose: The present study aims to report the occurrence of Eustrongylides sp. in some neotropical fish species commercialized in the Peruvian Amazonia. Methods: Samples of young farmed Arapaima gigas were collected from a fish farmer; young Brachyplatystoma tigrinum were acquired from a fish exporter and samples of adult specimens of Acestrorhynchus falcirostris, Pseudoplatystoma punctifer, Cichla monoculus, Hoplias malabaricus, Hydrolycus scomberoides, Raphiodon vulpinus, and Serrasalmus rhombeus were acquired from a fish market of Iquitos, Loreto-Peru. Samples were transported to the “Laboratorio de Parasiología y Sanidad Acuícola” from “Instituto de Investigaciones de la Amazonía Peruana” located in Iquitos, Peru. Results: Larvae L4 of Eustrongylides sp. were found in the host body, in the muscle, and in the visceral cavity of studied fish species. Notorious damages were reported in young A. gigas (lumps in the muscle, inflammation and severe redness of the skin) and in young B. tigrinum (perforation of the abdominal cavity), while in adult specimens of the remaining species, no external damage was reported. Conclusion: The presence of Eustrongylides sp. in various fish species collected in the city of Iquitos-Peru contributes to the distribution of this parasite in the Peruvian Amazon, reporting it, for the first time in this country. Its presence in the muscle of various fish species commercialized in fish markets, warm a possible public health concern and implications for their marketability in the city of Iquitos, Peru.