UTTAR PRADESH JOURNAL OF ZOOLOGY

Lead is a persistent aquatic pollutant that poses serious risks to fish health and ecosystem balance. This study examined the short-term effects of sublethal lead nitrate exposure on haematological indices, tissue morphology, cell viability, and coagulation dynamics in Anabas testudineus. The selected exposure concentrations (15 and 30 mg/L, respectively), representing sublethal fractions of the 96-h LC₅₀, were chosen to investigate early toxic responses under controlled laboratory conditions. Although these concentrations exceed those typically reported in natural freshwater systems, they provide valuable insight into the biological effects of acute lead contamination and potential pollution events. Lead exposure significantly reduced red blood cell count, haemoglobin, and haematocrit values, indicating anaemia and disrupted erythropoiesis. White blood cell profiles showed increased total counts and neutrophil levels but reduced lymphocyte and monocyte levels, suggesting concurrent inflammatory responses and immune suppression. Histopathological analysis revealed dose-dependent lesions, including renal glomerular shrinkage and tubular necrosis; hepatic vacuolation, sinusoidal congestion, and necrosis; and gill alterations such as epithelial hyperplasia, lamellar fusion, and hypertrophy. Overall, lead nitrate exposure caused systemic toxicity in A. testudineus, and the altered haematological and histopathological markers identified in this study may serve as useful indicators for ecotoxicological monitoring of heavy-metal contamination.