Parasitic diseases represent one of the most important problems in fish production
due to the decline of infected carcasses and public health problems due to the risk of
zoonoses, being scarce studies on fish parasites. This study identified the parasites,
using morphological and molecular techniques, and determined infection indicators,
of the collared Laemolyta garmani, Leporinus tigrinus, Argonectes robertsi and
Hemiodus unimaculatus the Tocantins River. Fifty four fish were adquired between
August and October 2015, anesthetized, euthanized and submitted to necropsy,
according to the Brazilian Good Practice Guide for Animal Euthanasy of the Federal
Board of Veterinary Medicine. The body surface, gills, abdominal cavity, heart, liver,
gallbladder, spleen, stomach, intestines, gonads and swimming bladder were
analyzed for the presence of parasites. A total of 461 specimens of parasites were
identified in 59.26% (32/54) of the fish collected. L. tigrinus presented infection by
two species of helminths, Goezia leporini, found in 16% of the animals and
Rondotrema microvitellarum in 8%. L. garmani presented infection by Spinitectus
rodolphiheringi (4%), Brasilnema sp. (28%), R. microvitellarum (16%) and Culuwiya
sp. (8%). The study reported for the first time the occurrence of the nematode
Spinitectus rodolphiheringi in the intestine of A. robertsi, with a prevalence of 7%, as
well the confirmation of the taxonomic classification by mitochondrial cytochrome C
subunit I phylogenetic analysis. Procamallanus inopitanus and Neochinorhychus sp.
were found in the intestine of H. unimaculatus. The identification of the parasites and
determination of their infection indicators allow to establishing appropriate
management methods, reducing infections in the animals, avoiding a decrease in the
commercial value and negative impact on the productive chain.
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