Assessment of Lambda‐Cyhalothrin Toxicity on Haematological, Biochemical and Histopathological Parameters in Freshwater Fish Labeo rohita

Lambda‐cyhalothrin (LCT) is a broad‐spectrum pyrethroid insecticide widely used in agricultural fields. The present study evaluated the haematological, biochemical, residue accumulation and histopathological effects of sublethal LCT exposure in Labeo rohita . The 96‐h LC 50 was determined as 0.116 mg/L. Fish were exposed to sublethal concentrations of 0.0038, 0.0058 and 0.0116 mg/L, corresponding to 1/30th, 1/20th and 1/10th of the LC 50 concentration, for 21 days. Sublethal exposure to LCT caused significant haematological alterations. Red blood cell count, haemoglobin, haematocrit and mean corpuscular volume decreased, whereas white blood cell counts increased significantly in a dose‐dependent manner. Mean corpuscular haemoglobin showed non‐significant changes. Glycogen content declined markedly in muscle and gut. However, similar reductions were observed in the liver and kidney, indicating energy depletion. Protein levels exhibited tissue‐specific responses: reductions in the kidney and brain, with other tissues showing non‐significant changes, indicating compensatory, organ‐specific metabolic adaptation. Serum biochemical parameters remained largely unchanged, except for a reduction in cholesterol to 0.0058 mg/L, possibly reflecting the lower sensitivity of enzymatic endpoints compared with tissue‐level alterations. GC–MS analysis confirmed dose‐dependent accumulation of LCT in muscle tissue. Histopathological alterations were observed in the gill, liver, kidney and brain tissues. Overall, the study presents integrated evidence of physiological, biochemical and histopathological detrimental effects on the organism.