Efficacy and toxicity of praziquantel in helminth-infected barbel (Barbus barbus L.).

This study evaluated efficacy and toxicity of the pyrazinoisoquinoline anthelmintic praziquantel (PZQ) in barbel infected with metacercariae of Diplostomum spathaceum and adult Pomphorhynchus laevis, and assessed antioxidant biomarkers and the lipid peroxidation response in juvenile barbel post-treatment. The estimated 96-hr LC50 of PZQ was 28.6 mg/L. For evaluation of efficacy, barbel naturally infected with D. spathaceum were exposed to a 10 and 20 mg/L PZQ 4-day bath treatment. Both concentrations were 100% effective against D. spathaceum and significantly (p < .01) affected the activity of catalase, superoxide dismutase, glutathione reductase and glutathione-S-transferase as well as levels of reduced glutathione in liver and muscle. The efficacy of orally administered PZQ was assessed in adult barbel naturally infected with P. laevis. Fish were administered 10, 30 and 50 mg/kg of body weight and examined via gut dissection after 6 days. The 50 mg/kg dose significantly decreased the intensity of infection. Praziquantel is a feasible bath treatment for barbel infected with D. spathaceum and has potential for oral treatment of broodfish infected with P. laevis.

Use of biometric, hematologic, and plasma biochemical variables, and histopathology to assess the chronic effects of the herbicide prometryn on Common Carp.

BACKGROUND: Effects of acute and subchronic exposure of fish to s-triazine herbicides have been well documented, but data on the effects of prometryn on blood analytes in carp at environmentally realistic concentrations are lacking. OBJECTIVE: The objective of the study was to determine whether biometrics, blood analytes, and histopathology could serve as bioindicators in fish living in waters polluted by triazine. METHODS: Fish were exposed to prometryn at concentrations of 0.51 (reported concentration in Czech rivers), 8.0, and 80 µg/L for 14, 30, and 60 days. Prior to and during this period, biometrics, blood analytes, and histopathology were evaluated. RESULTS: After 60 days' exposure to 8.0 and 80 µg/L of prometryn, spleen weights (P < .05) and lactate (P < .01) levels were significantly lower, and concentrations of HGB (P < .01) and MHC (P < .01) and MCHC (P < .01) were higher, relative to controls. After 30 and 60 days' exposure to 0.51, 8.0, and 80 µg/L of prometryn, AST activity, calcium, magnesium, and inorganic phosphate levels were lower (P < .01), while creatinine concentration and ALT activity were higher (P < .01) than in controls. Glucose was higher after exposure to 80 µg/L after 30 and 60 days, and after 60 days' exposure to 8.0 µg/L. Renal histology revealed severe hyaline degeneration of the epithelial cells of caudal kidney tubules in fish at all exposure levels. CONCLUSIONS: This study shows effects in fish blood at a concentration of 0.51 µg/L of prometryn, a significant finding in view of prometryn reaching a maximum of 4.4 µg/L or less in European rivers. Select blood analytes, such as creatinine, and histologic changes in caudal kidney are potential biomarkers for monitoring residual triazine pesticides in Common Carp.