Biological Science: Research Developments and Innovations Vol. 5

Freshwater fish integrate environmental stressors and can provide biological evidence of river condition. This study assessed spatial and seasonal patterns in six haematological indicators—haemoglobin (Hb), red blood cell count (RBC), white blood cell count (WBC), packed cell volume (PCV), mean corpuscular volume (MCV), and mean corpuscular haemoglobin concentration (MCHC)—in Channa striata collected from three locations in the Kharun River near Kumhari, Chhattisgarh: an upstream reference zone, an industrial-effluent meeting point, and a downstream zone. River water was assessed for Fe, Cd, Pb, Ni, and Hg, and the reported contamination gradient was considered alongside fish blood characteristics. Across summer, monsoon, and winter, Hb, RBC, PCV, MCV, and MCHC consistently decreased from upstream to downstream, whereas WBC increased. Downstream Hb was approximately 29% lower than upstream values, RBC was 36–39% lower, and WBC was 65–71% higher across seasons. When seasonal means were considered, downstream changes were approximately −29.0% for Hb, −38.1% for RBC, −27.5% for PCV, −14.2% for MCV, −19.9% for MCHC, and +68.2% for WBC. These coordinated responses are compatible with reduced oxygen-transport capacity and increased stress/immune activity. However, the field design does not establish causation by any single metal. The findings support the use of multi-parameter haematology as an early-warning component of freshwater biomonitoring while emphasising the need for cautious interpretation of mixed-contaminant field data.