Cestodes of the order Trypanorhyncha can frequently be found infecting the muscles of several marine fish species, and lead to a repugnant aspect of the fish and rejection by consumers. The Brazilian sardinella, Sardinella brasiliensis, occurs from the Gulf of Mexico and the Caribbean to northern Uruguay. In southeastern Brazil, fishing for the species is very intensive since it generates significant revenue as one of the most commonly consumed fish and an important element of the canned fish industry. The aims of the present study were to identify and report the occurrence of tiny cestodes (3 mm—6.6 mm) in the musculature of Brazilian sardinella that were purchased in the São Pedro fish market in the municipality of Niterói, state of Rio de Janeiro, Brazil. From October 2013 to November 2016, 75 specimens of S. brasiliensis were investigated. The trypanorhynch cestodes encountered were identified as plerocerci of Callitetrarhynchus gracilis using morphological, morphometric and molecular data. Parasitic indices were calculated, and the cestodes infection of the musculature of Brazilian sardinella had the following values: prevalence, 40%; mean intensity, 3.47; mean abundance, 1.39; and range of infection, 1–18, specimens. The presence of this trypanorhynch cestode in the musculature of Brazilian sardinella is an important indicator of fish hygiene.

Hyporthodus niveatus is an appreciated and valuable commercial fish species in the municipality of Niterói, state of Rio de Janeiro, Brazil, due its excellent quality flesh. The constant presence of helminths in the abdominal musculature, viscera and serosa of individuals of the species has been the subject of complaints among local fish traders because of economic losses due to their repugnant aspect. Considering their hygienic-sanitary importance and significance for collective health, the presence of helminths was investigated in 20 individual fish of H. niveatus purchased from fish markets in the municipality of Niterói in 2021-2022. Nematodes, identified as third-instar larvae of Contracaecum sp., Terranova sp., Hysterothylacium deardorffoverstreetorum and Raphidascaris sp., were found parasitizing the intestine and abdominal cavity. Acanthocephalans, identified as juveniles of Corynosoma australe, were found parasitizing the intestine. The highest parasitic indices were for H. deardorffoverstreetorum, with prevalence of 30%, mean intensity of 1.5, mean abundance of 0.45 and infection ranges of 1-2. Considerations about the zoonotic potential and hygienic-sanitary significance of these parasites are presented in order to increase food safety for consumers.