Presence of Contracaecum sp. larvae in two characiform fish from northeastern Brazil.

Pygocentrus nattereri Kner, 1858 and Serrasalmus rhombeus (Linnaeus, 1766) are species of serrasalmids sold in open-air markets and market municipalities in Maranhão, Brazil. Fifty-two individuals of P. nattereri and 52 of S. rhombeus were acquired from a fish market in the Municipality of Pinheiro,Maranhão, Brazil, and transported to the laboratory of "Inmunohistoquímica" from "Universidade Estadual do Maranhão" (UEMA). The lateral musculature of the fish was analyzed by making fine cuts, internal organs were placed in Petri dishes with distilled water, and with the aid of tweezers and needles, the tissue was examined by making fine cuts that allowed observation inside them. The results of the study revealed the presence of nematode larvae L3 of Contracaecum sp. was found parasitizing the visceral cavity, intestines, pyloric cecum, and stomach of P. nattereri and S. rhombeus. This study alerts local authorities and the population to take the necessary measures to prevent the accidental ingestion of endoparasites with zoonotic potential.