Effect of a 24-hour praziquantel bath on the haematological and biochemical profile and selected parameters of oxidative stress in grass carp (Ctenopharyngodon idella)

This study assessed the effect of a 24-hour bath with praziquantel (2 and 4 mg/l) on grass carp (<i>Ctenopharyngodon idella</i>) by monitoring thehaematological parameters, plasma biochemical profile, and oxidative stress indices. Fish were sampled at 24-, 48-, 72-, and 96-hours post-exposure (hpe). The haematologicalanalysis revealed a significant increase (<i>P</i> < 0.05) in the white blood cell count immediatelyafter treatment at both concentrations, with no subsequent changes. Within the plasma biochemical profile, a significant decrease (<i>P</i><i> < </i>0.05) was observedonly in chloride (24 hpeat 2 mg/l; 72 hpeat both concentrations) and in magnesium (48 hpeat 2 mg/l). The oxidative stress responses indicatedthat the gill was the most responsive tissue. In the gill, the catalase and glutathione-<i>S</i>-transferase activities increased significantly (<i>P</i><i> < </i>0.05) at 48 hpeat 4 mg/l. Lipid peroxidation in the gill decreasedat 48 hpe but increasedat 72 hpe following exposure to 4 mg/l. In the hepatopancreas, the glutathione peroxidase activity significantly decreasedat 48 hpeat 2 mg/l. In the plasma, significant changes (<i>P</i><i> < </i>0.05) were detected only in the ceruloplasmin activity, which decreased at 72 hpein the 2 mg/l group. These findings provide essential baseline data supporting the potential future application of praziquantel in aquaculture.