The phylum Nematoda is considered one of the most diverse groups in South America, as it is found in all habitats and is dynamic regarding the ecological characteristics of environments, this group becomes important for monitoring the state of ecosystems, thus making it of great importance. Its identification and occurrences in western Amazonia. Thus, the present study aims to present a list of fish nematodes in western Amazonia, as well as to describe their specific hosts. The study was carried out in the Alto Juruá region of the Western Amazon around the municipalities of Cruzeiro do Sul – Acre and Guajará – AM, Brazil. A total of 10,716 fish were collected, belonging to eight orders, 32 families and 216 species, with only 164 species showing nematodes. The species with the highest number of hosts were Procamallanus (S.) inopinatus Travassos et al., (1928), (67), Contracaecum sp....

The family Raphidascarididae is composed of nematodes that carry out their life cycle in environments using diverse intermediate or paratenic hosts including invertebrates, fish, waterfowl, and mammals. The genera of this family include Raphidascaris Railliet & Henry, 1915, Ichthyascaris Wu, 1949 and Sprentascaris Petter & Cassone, 1984; all can act as fish parasites. The objective of this work was to analyze host fish of the family Loricariidae including two species of zoonoticnematodes. The study was carried out in the municipality of Cruzeiro do Sul, Acre, Brazil. A total of 42 Sprentascaris mahnerti Petter & Cassone, 1984 was collected from three hosts of the family Loricariidae, 27 from Limatulichthys griseus Eigenmann, 1909, 10 from Spatuloricaria sp. Schultz, 1944 and 5 in Hypoptopoma steindachneri Boulenger, 1895. For Raphidascaris sp. Railliet & Henry, 1915 a tot...

The present study evaluated the Monogenea fauna parasitizing Trachelyopterus galeatus Linnaeus, 1766 (Cangati) and investigated the influence of environmental and morphometric factors on the abundance of these parasites. Six species of monogeneans were identified, with Ameloblastella sp. and Cosmetocleithrum sp. being the most prevalent and having the highest mean intensity. Ameloblastella sp. stood out significantly compared to the other species, suggesting greater adaptive and competitive efficiency. It was observed that 46% of the fish harbored two species of Monogenea, while 10% harbored four or five species, indicating the coexistence of these parasites. Despite variations in host weight, length, and condition factor, these characteristics showed no significant relationship with the abundance of Monogenea, suggesting that individual body factors are not determinants of the infestati...