“…For example, the serum concentrations after OTC immersion for rainbow trout (100 ppm for 1 hr) (Cobo Labarca et al., 2017), giant danio ( Devario aequipinnatus ) (100 ppm for 6 hr) (Vorbach, Chandasana, Derendorf, & Yanong, 2019), and gilthead seabream ( Sparus aurata ) (50 ppm for 24 hr) (Rigos, Nengas, & Alexis, 2006) were 0.050, 0.073, and 0.047 µg/ml, respectively, whereas the serum concentrations of FF in Nile tilapia after treating with similar concentrations and bathing duration were 0.22, 1.16, and 1.39 µg/ml, respectively. It should be pointed out that even the highest recommended concentration of OTC was applied (100 ppm bath) (Mashima & Lewbart, 2000; Noga, 2010; Wall & Wildgoose, 2005), the serum concentrations did not exceed 0.1 µg/ml (Cobo Labarca et al., 2017; Vorbach et al., 2019). Chelation between OTC and di‐/trivalent cations in the water may be an explanation for the low OTC uptake via the gill (Rigos & Smith, 2015).…”