Toxic effects of tin(II) chloride on hematological parameters and histopathology of gills and intestines in common carp (Cyprinus carpio)

Background and aims: Tin(II) chloride (SnCl₂) was selected because of its industrial applications and the potential release of inorganic tin into aquatic environments, motivating an assessment of its toxic effects in freshwater fish. Therefore, this study aimed to investigate the toxic effects of sublethal concentrations of tin chloride (SnCl₂) on blood parameters and gill and intestinal tissues of common carp.
Methods: For this purpose, we determined the 96-h median lethal concentration (LC₅₀) of SnCl₂ in common carp weighing 100 ± 8 g through an acute toxicity test conducted according to OECD Test Guideline 203. Then, 10, 25, and 50% of the LC50-96h were selected as sublethal concentrations of SnCl2. After the end of the experimental period (28 days), hematological and histological examinations were performed.
Results: The 96-h LC₅₀ of SnCl₂ was 131.82 mg/L. Compared with the control, red blood cell (RBC) counts decreased significantly, and white blood cell (WBC) counts increased significantly at 25% and 50% of the LC₅₀, whereas hematocrit (HCT) and hemoglobin (HGB) decreased significantly at 50% of the LC₅₀ (p < 0.05). Gill lesions included shortening and curvature of secondary lamellae, oedema, and necrosis. Intestinal changes included increased goblet cell numbers, goblet cell swelling, increased blood cell presence, and expansion of villous structures.
Conclusion: Under the experimental conditions, 28-day exposure to SnCl₂ was associated with altered hematological parameters and histopathological damage in the gills and intestines of common carp.