Assessment of Water Quality and Its Relationship with Fish Diversity

Abstract

Freshwater fish are like the river’s early warning system, they reveal more about water health than any single lab test. I selected three sites along the Ramganga River near Bareilly in Uttar Pradesh and sampled them monthly from June 2023 through November 2024, measuring dissolved oxygen, pH, BOD, Nitrates, Phosphates, Turbidity, and Coliforms. Fish assemblages were surveyed each season using electrofishing and gill nets. I found 22 fish species across 13 families. Urbanization left a clear mark. Site C, downstream of Bareilly, held only five species — all tough, pollution-tolerant survivors. Site A upstream had 14, including Catla catla and Tor tor, which only show up in clean, well-oxygenated water. The Shannon-Wiener index tracked this gap: 2.61 at Site A, 0.97 at Site C. Fish diversity correlated tightly with oxygen (r = 0.91, p < 0.01) and inversely with BOD (r = −0.87, p < 0.01).