Teflubenzuron as a tool for control of trichodinids in freshwater fish: Acute toxicity and in vivo efficacy

•TFB was effective on Trichodina heterodentata control in Piaractus mesopotamicus.•TFB was effective on T. magna, T. compacta e T. centrostrigeata in Oreochomis niloticus.•The most effective TFB concentration was those which obtained the higher survival rate.•TFB has not caused physical and chemical alterations on the water during the treatment.•TFB was practically non-toxic for O. niloticus and P. mesopotamicus. In this study we describe the anti-Trichodina effects of teflubenzuron (TFB) for Oreochromis niloticus and for Piaractus mesopotamicus. We also evaluated the acute toxicity, for both species, by using TFB in the concentrations of 700.0, 800.0, 900.0 and 1000.0 mg L−1 and a control, without the drug. To assess the efficacy of TFB against Trichodina spp., we used the concentrations of 30.0 or 50.0 mg L−1 for one hour exposure in tilapia, and the concentration of 30.0, 50.0 and 80.0 mg L−1 for one hour and 50 mg L−1 for two hours exposures in pacu. Teflubenzuron did not present significant toxicity in either species, with LC50;48h > 1000.0 mg L−1. The drug effectiveness was observed against four identified Trichodina species: T. magna, T. heterodentata, T. compacta and T. centrostrigeata, with 87.9% parasite reduction with one hour exposure to 50.0 mg L−1 TFB on O. niloticus and 96.1% with two hours exposure to 50.0 mg L−1 TFB on P. mesopotamicus. Teflubenzuron is a drug with potential to be used in Brazilian aquaculture; it attends to important requirements, such as low toxicity and high efficacy in controlling Trichodina spp. infection in O. niloticus and P. mesopotamicus.