Antiparasitic efficacy of dietary administration of trichlorfon (Masoten®) in the control of Neoechinorhynchus buttnerae (Neochinorhynchidae) in Colossoma macropomum (Serrasalmidae)

Abstract

This study investigated the efficacy of trichlorfon against Neoechinorhynchus buttnerae, as well as its palatability, residue analysis, and the blood parameters of Colossoma macropomum. At the beginning of the experiment, all previously examined fish were infected with N. buttnerae. There were no differences in mean intensity and mean abundance of N. buttnerae within each treated group and the control group; however, efficacy of 53.4% was found in fish fed with diets containing 1.0 g kg−1 of trichlorfon. Treated fish presented an increase in plasma glucose, while fish fed with diets containing 0.75 and 1.0 g kg−1 of trichlorfon presented an increase in plasma alanine aminotransferase levels. In the higher of the two concentrations, an increase in plasma aspartate aminotransferase levels also occurred. After 96 h, trichlorfon residues were found in the muscle of fish fed with diets containing 0.75 and 1.0 g kg−1 of trichlorfon. No mortality of fish was observed; however, since adverse reactions occurred, and due to palatability problems associated with treatments, 1.0 g kg−1 of trichlorfon could be used for 15 days to control infections by N. buttnerae, though, due to the risk of toxicity, this treatment is not recommended for regular use. As such, precautions should be taken even when using low concentrations of trichlorfon for treatments against this acanthocephalan, as well as in relation to the period of elimination of the trichlorfon residues from fish muscle in order to guarantee safe consumption. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.