To obtain the desired concentration of Folidol 600, the necessary
volume of the substance (1 mg/Folidol 600/ml) was calculated
for each volume of respirometer and added with a
micropipette at the end of the acclimation period. As soon as the
substance was added, the entry orifice was immediately sealed.
After, the actual concentration of parathion was measured by
chemical methods. Additionally, the seawater in the respirometer
was sampled at the beginning and at the end of the oxygen consumption
analysis. Determination of ammonium–nitrogen in the
seawater was based on the phenolhypochlorite method [28]. The
average oxygen-specific consumption and ammonium excretion
by the fish was assessed using analysis of variance. All data were
analyzed using the Tukey’s multiple comparisons test (p < 0.05).