Question

why do fish die due to the excessive water pollution

Answer 1

The most common cause is reduced oxygen in the water, which in turn may be due to factors such as drought, algae bloom, overpopulation, or a sustained increase in water temperature. Infectious diseases and parasites can also lead to fish kill. Toxicity is a real but far less common cause of fish kill.

Answer 2

because when we use detergents that water mix with the river water n that will decrease the quantity of oxygen in water from this the fish will die