*2.1. Detected Levels as Well as Rates of Residues of Sulfonamides in Analyzed Fish Samples*

In total, 52 fish samples were analyzed. Table 1 presents the detected levels of banned sulfonamide residues in different fish samples. In all fish samples, the predominant sulfonamide residue was sulfamethazine (Figure S1): 5% in tilapia (1/20; concentration: 0.03 mg/kg) and 6.25% in milk fish (1/16; concentration: 0.02 mg/kg). The data for the remaining 19 tilapia, 15 milk fish, and 16 perch samples, which did not demonstrate detectable levels of sulfonamides, are not shown. Moreover, on average, 0.002, 0.001, and 0 mg/kg sulfonamides were detected in all tilapia, milk fish, and perch samples, respectively. Finally, only 2 (3.85%) of all 52 samples contained sulfonamides (i.e., sulfamethazine).


**Table 1.** Detected levels of residues of prohibited sulfonamides in fish samples collected over June 2018 to October 2019.

<sup>1</sup> Values are given as means ± SEM. <sup>2</sup> Estimated for all samples (detected and not detected to have sulfonamide residues). <sup>3</sup> Samples with residual concentrations lower than the limit of quantification were considered to have undetectable concentrations.

#### *2.2. Detection Levels and Rates of Organophosphorus Insecticide Residues in Fish Samples*

Table 2 presents the detected levels of the residues of prohibited organophosphorus insecticides in different fish samples. In all fish samples, the predominant organophosphorus insecticide residue was of chlorpyrifos (Figure S2): 5% in tilapia (1/20; concentration: 0.02 mg/kg), 6.25% in milk fish (1/16; concentration: 0.05 mg/kg), and 6.25% in perch (1/16; concentration: 0.03 mg/kg). The data of the remaining 19 tilapia, 15 milk fish, and 16 perch samples, which did not demonstrate detectable levels of organophosphorus insecticides, are not shown. That is, in general, the detected levels of chlorpyrifos were between 0.02 and 0.05 mg/kg. Moreover, on average, 0.001, 0.003, and 0.002 mg/kg chlorpyrifos were detected in all tilapia, milk fish, and perch samples, respectively. Finally, only 3 (5.77%) of all 52 samples contained sulfonamides (i.e., sulfamethazine).


**Table 2.** Detected levels of residues of organophosphorus insecticides in fish samples obtained over June 2018 to October 2019.

<sup>1</sup> Values are given as means ± SEM. <sup>2</sup> Estimated for all samples (detected and not detected to have organophosphorus insecticide residues). <sup>3</sup> Samples with residual concentrations lower than the limit of quantification were considered to have undetectable concentrations.
