Question

How does dumping sewage into the water bodies affect the fishes in it?

• A. Fish and other aquatic animals die due to the bad odour
• B. It replaces food material of fishes
• C. It increases $O_2$ competition among the fishes
• D. The nitrogen content of the water decreases.

Answer 1

The correct option is C It increases $O_2$ competition among the fishes

Sewage is made up of both biodegradable and non-biodegradable wastes which do not dissolve in water. It, in turn, increases the water pH and the COD and BOD level hence decreasing the oxygen content of water. As the oxygen content decreases most of the fish die due to lack of oxygen.