Behavioral, Hematological, Biochemical, Antioxidant, Histopathological and Micronuclear Abnormality in the Erythrocytes of Ctenopharyngodon idella Exposed to Chromium Chloride Toxicity

Chromium is characterized by toxicity to living organisms due to their ability to accumulate in biological tissues and disrupt normal physiological functions. The current study assessed the effect of chromium on the serum biochemistry, hematology, antioxidant enzyme system, and histopathology of the selected freshwater fish (Ctenopharyngodon Idella). For this purpose, Ctenopharyngodon Idella, weighing ∼60–80 g, were divided into four groups at random and subsequently subjected to chromium exposure i.e. control, 0.44 mg L⁻¹, 0.89 mg L⁻¹ and 1.34 mg L⁻¹ from LC₅₀ (74.35 mgL^− 1) for 21 days and data was taken after 7, 14, and 21 days. Results showed a significant effect of treatment and duration on fish body weight (p < 0.05). A significant increase in leukocytes and heterophils was observed between the treated groups which showed a significant decrease in red blood cell count, hemoglobin, hematocrit, mean corpuscular hemoglobin, mean corpuscular volume, and lymphocytes. Significant reductions (p < 0.05) were observed in serum biochemical parameters such as total proteins, albumin, and globulin. Conversely, the treated groups exhibited significant increases (p < 0.05) in alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), glucose, and cholesterol compared to the control group. Decreased values of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in the kidney and gills tissues of fish were recorded. The micronucleus (MN) assay confirmed genotoxicity, revealing elevated frequencies of nuclear abnormalities such as notched, condensed, binucleate, pear-shaped nuclei, and micronuclei. There was a noticeable rise in the frequencies of nuclear irregularities within the erythrocytes. The presence of altered nuclei suggests that chromium chloride might be causing damage to the cells and their genetic material. The histopathological analysis of fish gills and kidneys revealed inflammation and degenerative alterations attributed to exposure to chromium. Within kidney tissues, there was an increase in degenerative changes such as expansion of Bowman’s space, necrosis of tubular cells, and deterioration of the glomerulus. Congestion, Lamellar fusion, and Lamellar disorganization were observed in the gill’s tissues exposed to chromium. In conclusion, the study indicates that exposure to chromium chloride, even in smaller concentrations, can cause adverse hematological and histopathological changes in Ctenopharyngodon Idella.